RE: Mersenne: christmas computer system?
Get a P4 motherboard that supportes DDR333 (PC2700). Then buy the Extreme PC2700 memory from www.corsair.com. It has a significant performance-enhancing feature: 2.0 cycle latency versus the more standard 2.5. This high-performance Corsair memory only costs a few bucks more than standard PC2700 sticks. (I'm sure other people make CL2.0 sticks, I just haven't found them anywhere for purchase.) Any decent white-box manufacturer should be able to find you PC2700 DDR with CAS2.0. Ryan Malayter Sr. Network Database Administrator Bank Administration Institute Chicago, Illinois, USA PGP Key: http://www.malayter.com/pgp-public.txt ::: Twas a woman who drove me to drink. I never had the courtesy to thank her. -W.C. Fields -Original Message- From: Russel Brooks [mailto:[EMAIL PROTECTED]] Sent: Sunday, November 24, 2002 9:55 AM To: [EMAIL PROTECTED] Subject: Mersenne: christmas computer system? I'm giving my brother's family a new computer for christmas. He'll buy it from a local (to him) 'white box' pc store and I'll pay for it. I am a little concerned about performance because the pc will probably be running GIMPS and I'd like to get my money's worth. It's easy to request a P4 in the 2.0-2.5 range and 256M-512M of memory but I've read of the bottleneck caused by slow memory and the bus between memory and cpu and I don't know what to specify or how to evaluate components in this area or measure performance after the pc is built. Any comments or suggestions? I want them to have a fast machine but not on the bleeding (expensive) edge. Other than GIMPS I'm sure my nephew will be the heaviest load when he plays games on the new machine. I think I should also request the video card has all of it's own memory, right? I don't want the video to share the main memory for performance reasons, right? Cheers... Russ DIGITAL FREEDOM! -- http://www.eff.org/ _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: christmas computer system?
Personally, I just ordered a brand spankin' new Compaq server (ugh... HP server now) with dual P4 Xeon 2.8 GHZ processors, 3GB of RAM. I can't wait to get my hot little hands on that and see just how well it crunches the #'s. It's memory is 200MHz DDR (FSB is 400MHz), advanced ECC (Compaq's version of ECC... Detect 4 bit and corrects 2 bit errors, as opposed to detect 2, correct 1 with normal ECC). Anyone on here had any hands on experience with the 2.8 GHz Xeon's yet? Have they been benchmarked? Aaron _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: christmas computer system?
From: John R Pierce [mailto:[EMAIL PROTECTED]] the fastest P4 cpus have a rated FSB of 533 (which is 266*2). running the bus at 333(666) would be overclocking. No, it wouldn't. I don't think you understand how the memory architecture of a modern Intel chipset works. The memory clock speed is independent of the FSB speed. The front-side bus connects the CPU to the Northbridge of the chipset. The chipset, in turn, has a separate bus to connect to memory. See this link for an example diagram of a modern P4 chipset: http://www.tomshardware.com/mainboard/02q2/020514/p4x333-04.html Ryan Malayter Sr. Network Database Administrator Bank Administration Institute Chicago, Illinois, USA PGP Key: http://www.malayter.com/pgp-public.txt ::: Twas a woman who drove me to drink. I never had the courtesy to thank her. -W.C. Fields _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: christmas computer system?
the fastest P4 cpus have a rated FSB of 533 (which is 266*2). running the bus at 333(666) would be overclocking. Ah, but most modern mobos can run the memory asynchronously to the processor bus. I think this goes back some way - certainly the Abit KT7A board (Athlon) could run the memory bus at either FSB or FSB+PCI rate ... So you _can_ run memory at 166 MHz double-pumped and the FSB at 133 MHz quad-pumped without over- or under-clocking anything. ok, true. I forgot VIA is allowing this. AFAIK, the i845pe doesn't support memory faster than the CPU FSB (it allows SLOWER memory, the older i845e only supported 100/200Mhz DDR w/a 133/266/533 CPU bus). I have had so many bad experiences with VIA based systems and poor PCI and AGP I/O performance that it will be a long time before I consider one again, regardless of claimed CPU benchmark performance. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: christmas computer system?
From: John R Pierce [mailto:[EMAIL PROTECTED]] ok, true. I forgot VIA is allowing this. AFAIK, the i845pe doesn't support memory faster than the CPU FSB (it allows SLOWER memory, the older i845e only supported 100/200Mhz DDR w/a 133/266/533 CPU bus). Look again... the 845PE and 845GE do, in fact, support DDR333 as well as DDR266 memory with a 533 MHz FSB. See: http://www.intel.com/design/chipsets/845pe/index.htm?iid=ipp_dlc_chip+de skchip_845pe I have had so many bad experiences with VIA based systems and poor PCI and AGP I/O performance that it will be a long time before I consider one again, regardless of claimed CPU benchmark performance. I used to agree with you. Heck, I used to have the same stability bias against AMD-based systems. However, the small guys usually offer new chipset chipset features and performance levels several months before Intel, so we gave a few 3rd party boards another tryout. I've had no trouble with any of the recent (last 2 years or so) VIA-based or SiS-based motherboards my company has purchased. We always buy Asus, who seems (in my experience) to make the most stable MoBos besides intel. You might want to give them another chance. Regards, -ryan- _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: christmas computer system?
You definitely want the video card with it's own memory. If you feel like doing some reading go to http://www.tomshardware.com Lots of info on the newest (and not so new) hardware there. Matt -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Russel Brooks Sent: Sunday, November 24, 2002 8:55 AM To: [EMAIL PROTECTED] Subject: Mersenne: christmas computer system? Any comments or suggestions? I think I should also request the video card has all of it's own memory, right? I don't want the video to share the main memory for performance reasons, right? Cheers... Russ _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: christmas computer system?
I'm giving my brother's family a new computer for christmas. He'll buy it from a local (to him) 'white box' pc store and I'll pay for it. I am a little concerned about performance because the pc will probably be running GIMPS and I'd like to get my money's worth. It's easy to request a P4 in the 2.0-2.5 range and 256M-512M of memory but I've read of the bottleneck caused by slow memory and the bus between memory and cpu and I don't know what to specify or how to evaluate components in this area or measure performance after the pc is built. Any comments or suggestions? for P4 systems, from fastest (most $$) to slowest (cheapest) it goes, RDRAM, DDR SDRAM, regular PC133 SDRAM. I'd suggest getting the DDR SDRAM. The Intel i845PE chipsets support this. I want them to have a fast machine but not on the bleeding (expensive) edge. Other than GIMPS I'm sure my nephew will be the heaviest load when he plays games on the new machine. I think I should also request the video card has all of it's own memory, right? I don't want the video to share the main memory for performance reasons, right? yeah, get a NVIDIA Geforce based graphics card... ATI might have won the latest round of benchmark wars, but NVIDIA has better driver stability. If you're going way cheap, get a GF3, more expensive get one of the slower steppings of the GF4 Ti (note that the budget GF4 MX is really a GF3 grade board, its kinda confusing). my shopping list for a reasonably priced high quality P4 right now is, with prices from my local cloneshop (not the cheapest place, but good service)... $213 Intel Retail P4-2.4B (these have the 533MHz bus) $133 Asus P4PE/L (i845pe chip, integrated ethernet and audio) $158 Samsung 512MB PC2700 DDR SDRAM $163 Asus V8420 GF4 Ti 4200, 128MB $113 Seagate Baracuda ATA IV 80GB disk (super quiet, very fast) $48 Toshiba 16X DVD-ROM $83 Teac CDW540E 40/12/48 cd-rw burner $8 Mitsumi floppy $78 Enlight mid-tower $23 Microsoft Intellimouse Optical OEM $9 Mitsumi generic 104 keyboard $1030 total for a 2.4Ghz 512MB machine with 80GB of disk, DVD-ROM and CD burner. This does NOT include the monitor, printer, or speakers, as those are all highly subjective. I also didn't include a modem, there's ethernet on the motherboard.. if these guys use dialup... now, if you need to trim corners, A) back off on the video card, get a GF4MX, B) back off to 256MB ram, thats enough, 512 is a luxury, if needed it could be added in. C) get a cheaper case. D) drop the DVD, you can always add one in later. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: christmas computer system?
On Sunday 24 November 2002 15:55, you wrote: (B I'm giving my brother's family a new computer for christmas. (B He'll buy it from a local (to him) 'white box' pc store and I'll (B pay for it. I am a little concerned about performance because (B the pc will probably be running GIMPS and I'd like to get my (B money's worth. It's easy to request a P4 in the 2.0-2.5 range (B and 256M-512M of memory but I've read of the bottleneck caused (B by slow memory and the bus between memory and cpu and I don't (B know what to specify or how to evaluate components in this area (B or measure performance after the pc is built. (B (B Any comments or suggestions? (B (BWell - one of the key things with P4 systems is that the processor needs to (Bbe properly cooled. If it isn't, the reliability will probably be OK, but the (Bperformance will suffer as the processor goes into thermal throttle mode. (B (BUnfortunately many "fashion" systems come in unreasonably small cases with (Bgrossly inadequate ventilation, and an underspecified heat sink. Most users (Bnever notice that the system is throttled, because even at quarter speed, a 2 (BGHz P4 is more than powerful enough for everyday tasks like word processing, (Beven using M$'s mega-bloated packages. Also, shifting sufficient air to cool (Ba P4 (or a high-end Athlon) properly means either a large, heavy and (Bexpensive heat sink, or a noisy fan. (B (BBasically my advice would be to go for build quality rather than raw (Bperformance. If the thing is properly built, you will at least be able to do (Bsomething about any deficiencies. (B (BI would reject out of hand any package containing peripherals which are (Bdesigned to work only with Windows, or which has Windows pre-installed with (Bonly a "system recovery" CD rather than proper installation media. I'd far (Bprefer to take a system without Windows bundled at all, but M$ tries to make (Blife miserable for system builders who try to avoid the "Microsoft tax". (B (B I want them to have a fast machine but not on the bleeding (B (expensive) edge. (B (BThe problem here is that most "big name" systems builders keep changing the (Bimportant components (motherboard, graphics card etc) to suit their profit (Bmargins and stock availability. You will find apparently identical systems, (Bwith the same "top line" specification, are quite different inside and may (Bhave very different performance. (B (BSo ... look for something that at least tells you what the mainboard chipset (Bis. This will give you a good indication of the performance _potential_ and (Bupgradeability of the system. (B (BPersonally - although this is distinctly unfashionable - I far prefer Rambus (Bmemory - so far as GIMPS is concerned, a 2.53 GHz P4 using PC1066 Rambus (Bmemory (implying the i850E chipset) will outperform _any_ system up to 2.8 (BGHz using DDR memory. The point here is that the total memory bandwidth of (Bthe Rambus system is 4200 Mbytes/sec, whereas even using 400 MHz DDR memory (B(just as rare expensive as PC1066 Rambus memory) you are only going to get (B3200 MBytes/sec. (B (BIf you're forced to a DDR based system, then look for the Intel 845PE (Bchipset. (This also supports the new P4 processors up to at least 3.06 GHz (Bwith hyperthreading support enabled). With chipsets using DDR, there is (Bpotential for inefficiency by using slow memory - e.g. KT400 chipset should (Balways be used with 400 MHz memory (PC3200), KT333 with 333 MHz memory (B(PC2700) etc. This is because the "gearchange" caused by using slower memory (Bthan the chipset supports kills performance. Installing faster memory than (Bthe chipset supports is OK (except that Rambus systems supporting only PC800 (BRDRAM do _not_ work with PC1066 memory) but not often done for reasons of (Bcost. (B (BThe problem here is that few "big name" manufacturers will tell you the (Bspecification of the components have gone into a system, and even fewer sales (Bassistants in the retail stores where they're sold will understand (Bintelligent questioning. (They _may_ understand raw MHz, disk capacity, (Bmonitor size etc., but that's about the limit of what you should expect.) (B (BIf you really want performance, and are prepared to cut back on things you (Bdon't need (superfluous peripherals, bundled software etc), then it is (Bpractically essential to "roll your own", or (at a premium) go to a small, (Bspecialist systems builder armed with a specification. Building the thing (Byourself is satisfying, too. (B (B Other than GIMPS I'm sure my nephew will be the heaviest load (B when he plays games on the new machine. (B (BSo you want a darned good graphics card ... a weak graphics card will kill (Bgames performance much more than a poor mainboard/processor/memory (Bcombination. Many games players also insist on a good sound system. (B (B I think I should also request the
Re: Mersenne: christmas computer system?
Personally - although this is distinctly unfashionable - I far prefer Rambus memory - so far as GIMPS is concerned, a 2.53 GHz P4 using PC1066 Rambus memory (implying the i850E chipset) will outperform _any_ system up to 2.8 GHz using DDR memory. The point here is that the total memory bandwidth of the Rambus system is 4200 Mbytes/sec, whereas even using 400 MHz DDR memory (just as rare expensive as PC1066 Rambus memory) you are only going to get 3200 MBytes/sec. I'm just curious, were those RDRAM vs DDR benchmarks done using the newer 512K cache P4 chips? The larger cache should, at least in theory, serve to partially mitigate the slower memory bus. Also, DDR has lower latency than RDRAM, which somewhat offsets the slower burst rate. pricewise, again using the local cloneshop I got the previous prices from, replace the motherboard and ram like so... -$133 Asus P4PE/L (i845pe chip, integrated ethernet and audio) -$158 Samsung 512MB PC2700 DDR SDRAM +$173 Asus P4T533-C/Lan (i850e w/ sound and ethernet) +$308 Samsung 512MB PC1066 RDRAM for a net difference of ~ $200, pushing the total to $1230. btw, lotsa folks will disagree with me, but I find onboard sound to be more than sufficient for 99% of users actual needs unless you are hooking this system up to a goldenears audiophile system, you aren't gonna hear the difference, and I've had *SO* much trouble with the proprietary drivers for the likes of Sound Blaster Live and Audigy cards that I will never touch another one. btw, I left out an important piece of the whitebox system... $148 Microsoft Windows XP Professional OEM (if you buy this WITH the system, you save $100 over the retail version) There is two key features of PRO vs Home that makes it worth the extra $50 to me... A) Remote Desktop, and B) Security. XP Home's security model is way too braindamaged. XP Pro's Remote Desktop Services is far superior to 3rd party remote control packages such as PC/Anywhere, or VNC. The 3rd key difference is dual processor support, which won't matter on a single CPU system like this. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: christmas computer system?
On Sunday 24 November 2002 18:47, John R Pierce wrote: my shopping list for a reasonably priced high quality P4 right now is, with prices from my local cloneshop (not the cheapest place, but good service)... $213 Intel Retail P4-2.4B (these have the 533MHz bus) 2.53B should be very little more expensive. Last time I checked the first big price step was still between 2.5A/2.53B and 2.6A/2.66B. The other point here is that P4s don't seem to benefit much (if at all) from 533MHz FSB except with 533 MHz RDRAM. Even at 400 MHz, DDR throttles the CPU/memory bus to the point where the CPU/chipset clock rate is unimportant. Consider spending a bit more on a Zalman Flower Cu/Al S478 heatsink variable speed fan. Even with the fan turned down to minimum, at which speed it is truly inaudible, it's at least as effective as the retail box HSF. $133 Asus P4PE/L (i845pe chip, integrated ethernet and audio) $158 Samsung 512MB PC2700 DDR SDRAM $163 Asus V8420 GF4 Ti 4200, 128MB Personally I _love_ the Matrox G400/G450/G550 video card. Cheaper, unsurpassed 2D display, drivers superbly stable. But then I'm not a games freak. $113 Seagate Baracuda ATA IV 80GB disk (super quiet, very fast) $48 Toshiba 16X DVD-ROM I could easily do without the DVD drive. $83 Teac CDW540E 40/12/48 cd-rw burner Seems a bit expensive. There's little point in going for superfast write/rewrite performance; either you can't get media much faster than 24xW / 8xRW, or you can't justify the price premium. $8 Mitsumi floppy If I can boot from a CD, I don't need a floppy drive any more. Spend the money on a couple of round IDE cables instead. (Neater, less air flow obstruction) $78 Enlight mid-tower IMHO money spent on the case is money well spent. On my previous experience with Enlight cases, if you buy one you should also buy a box of sticking plasters. I always seemed to end up with shredded fingers whenever I worked inside them. There are cheaper, nastier cases with even sharper edges, but I don't reccomend them, either. These days I use Coolermaster ATC200 (comes fitted with 4 quiet 8 cm fans) and Enermax 350W PSU (dual fan; thermally controlled inlet, manual variable speed exhaust). I don't know the current US price but the case PSU come to around £180 retail here (so probably $180ish?). For that you get an all-metal case with superb build quality, excellent cooling with barely audible fan roar and really smart styling. It's a normal-size mini-tower case but will accomodate _at least_ 6 3.5 drives without touching the 3 5.25 bays. A good case will survive a few PC generations. $23 Microsoft Intellimouse Optical OEM $9 Mitsumi generic 104 keyboard I _hate_ membrane keyboards would not pay even 9 cents for any of them... If you can, get a genuine late -1980s IBM PS/2 keyboard from a scrapyard / car boot sale rather than buy a new one. It will be more reliable as well as much more comfortable to use. I think Cherry still make a proper mechanical switch keyboard with a decent action, but it's _very_ expensive (well over £50). Regards Brian Beesley _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: christmas computer system?
(yet more PC hardware details below... feel free to skip this if isn't your thing...) $213 Intel Retail P4-2.4B (these have the 533MHz bus) 2.53B should be very little more expensive. Last time I checked the first big price step was still between 2.5A/2.53B and 2.6A/2.66B. my store wants $50 more for the 2.53B over the 2.4B. The A versions are pretty much history. seemed a bit more than 133Mhz is worth (~5% faster), to me anyways. OTOH, $50 is about 5% of the total system price, so thats a judgement call. The other point here is that P4s don't seem to benefit much (if at all) from 533MHz FSB except with 533 MHz RDRAM. Even at 400 MHz, DDR throttles the CPU/memory bus to the point where the CPU/chipset clock rate is unimportant. I'm pretty sure the newer i845PE chipset runs the 533Mhz FSB with the DDR at 266/533 ? I'd sure think that would scale nicely over a 200/400 memory bus. Yes, the PC1066 RDRAM stuff is running the memory at 533/1066, however, its a narrower bus, so that offsets the speed boost. the DDR ram is 64 bits wide, same as the CPU, while the RDRAM is 32bit and has to double-cycle to supply one CPU cycle. Consider spending a bit more on a Zalman Flower Cu/Al S478 heatsink variable speed fan. Even with the fan turned down to minimum, at which speed it is truly inaudible, it's at least as effective as the retail box HSF. OTOH, I've never had any problem with any CPU with the retail Intel heatsinks. Their retail CPUs have a better warranty than the OEM ones (where the warranty if any is between you and the reseller). $133 Asus P4PE/L (i845pe chip, integrated ethernet and audio) $158 Samsung 512MB PC2700 DDR SDRAM $163 Asus V8420 GF4 Ti 4200, 128MB Personally I _love_ the Matrox G400/G450/G550 video card. Cheaper, unsurpassed 2D display, drivers superbly stable. But then I'm not a games freak. NVIDIA has owned the 3D sector now for quite some time. Their OpenGL implementation is excellent, quite usable for scientific and CAD graphics in addition to gaming. The 2D performance of NVIDIA cards is quite good anyways, and they do a very nice job on video playback and stuff like that. $113 Seagate Baracuda ATA IV 80GB disk (super quiet, very fast) $48 Toshiba 16X DVD-ROM I could easily do without the DVD drive. I've been having fun ripping rock video trailers off of various DVD movies I own and turning them into MPEGs for my own amusement. Mostly as an experiment... more seriously, however, I've been seeing more and more things that formerly required multiple CDs showing up on DVDrom. Certainly, having 4GB+ on a single disk beats 5 660MB CDs that you have to flip through for a mapping database or something. Also, I do enough CD - CD things that I find having two drives is very convenient, I'd use the dvd as the primary reader, and mostly use the CD-R as a burner. $83 Teac CDW540E 40/12/48 cd-rw burner Seems a bit expensive. There's little point in going for superfast write/rewrite performance; either you can't get media much faster than 24xW / 8xRW, or you can't justify the price premium. those are very fast CD readers too... I dunno CD-RW, never had much use for them, but the bulk TDK blanks I get at Costco seem to burn 100% AOK at 40X, and you can make a 700MB data backup in just a couple of minutes. $8 Mitsumi floppy If I can boot from a CD, I don't need a floppy drive any more. Spend the money on a couple of round IDE cables instead. (Neater, less air flow obstruction) I get these for last ditch hardware diagnostics if nothing else. I hate having to dink around with building a bootable CD of something like GHOST, or MEMTEST32. $78 Enlight mid-tower IMHO money spent on the case is money well spent. On my previous experience with Enlight cases, if you buy one you should also buy a box of sticking plasters. I always seemed to end up with shredded fingers whenever I worked inside them. There are cheaper, nastier cases with even sharper edges, but I don't reccomend them, either. The recent Enlight cases I've seen have had all inside edges nicely dressed, and they are a bit better at airflow than the Inwin cases I've used extensively in the past. These days I use Coolermaster ATC200 (comes fitted with 4 quiet 8 cm fans) and Enermax 350W PSU (dual fan; thermally controlled inlet, manual variable speed exhaust). I don't know the current US price but the case PSU come to around £180 retail here (so probably $180ish?). For that you get an all-metal case with superb build quality, excellent cooling with barely audible fan roar and really smart styling. It's a normal-size mini-tower case but will accomodate _at least_ 6 3.5 drives without touching the 3 5.25 bays. The ATC201c-SX shows 4 5.25, 2 floppies, plus 4x3.5 internal, and the 4x80mm fans, but no PSU for $143 at my local store. A Antec or Entex 350W PSU will add $50 or $60. Those are very nice cases, for sure, but the price premium is quite steep
Re: Mersenne: christmas computer system?
John R Pierce wrote: $83 Teac CDW540E 40/12/48 cd-rw burner Seems a bit expensive. There's little point in going for superfast write/rewrite performance; either you can't get media much faster than 24xW / 8xRW, or you can't justify the price premium. those are very fast CD readers too... I dunno CD-RW, never had much use for them, but the bulk TDK blanks I get at Costco seem to burn 100% AOK at 40X, and you can make a 700MB data backup in just a couple of minutes. I just wanted to point out that if you live in the US and are looking to get a CD-RW drive and/or media, do your shopping on Black Friday (the Friday after Thanksgiving.) For example, Best Buy will be offering a 48x12x48 for $9.99 after several mail-in rebates, and a bundle of 150 40X speed CDR blanks for free after mail-in rebate ($26 before rebate.) Other stores are having similar deals, Staples, Office Max, etc. Lots of stuff really cheap (especially DVD-ROMs / CD-RWs / media) or even free after all the mail-in rebates are applied. Brian _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
