Following a market search, i have to reformulate my question by replacing GTX-470 with GTX-570. The former seems to have nearly disappeared, or i costs nearly as much as the latter. francesco pietra
---------- Forwarded message ---------- From: Francesco Pietra <chiendar...@gmail.com> Date: Sat, May 14, 2011 at 8:06 AM Subject: Re: workstation for CUDA To: Lennart Sorensen <lsore...@csclub.uwaterloo.ca> Hi: in the meantime i had the opportunity to carry out my simulations on both a high-end tesla gpu computer and a very simple consumer-type computer based on a single gtx-470, both running on debian amd 64 lenny. As all classical molecular dynamics codes are compiled for single precision, there was no advantage with the tesla, actually, gxt-470 run a bit faster when comparing 1:1 graphics cards number. Therefore, as all expenses for this computer will be supported by myself, i am looking for up-to-date consumer components, except the power source, hard disks and fans, which should be server-type. Ideally, the motherboard should support four gtx-470, less if no such consumer motherboard exists. No X server will be installed, graphics being examined at a ssh-linked desktop. From this, the choice of the cpus and the power source descends. As the simulations last many days, the cage must have place for many, large-diameter, fans, for use in the open air. With a server-type, four socket cpu machine that i set up a few years ago, there are eleven fans on the cage and no air cooler was ever needed at the latitude i am based. i am particularly embarrassed any time i have to select hardware, especially here. Such type of computations require little ram (a few gb in the four-gtx470 case), performance being entirely to the cpu/gpu. I understand that a consumer motherboard may well be a bottle-neck, and should not. This explains my difficulty in the choice of the essential haraware. i am prepared to accept a compromise in the performance thanks a lot for advice francesco pietra On Wed, Jan 26, 2011 at 7:27 PM, Lennart Sorensen <lsore...@csclub.uwaterloo.ca> wrote: > On Tue, Jan 25, 2011 at 05:00:51PM -0500, Lennart Sorensen wrote: >> Most boards technically don't have enough bandwidth. However when >> they use the NF200 PCIe switch, it tends to work quite well. The NF200 >> actually allows broadcast of the same data to multiple cards if that is >> what is needed. Each card has potentially 16 lanes, but it is sharing >> with another card for those 16 lanes. If you are sending data to just >> one card, it will get full speed. If you are sending to both at once, >> they get half speed, unless you are sending the same data to both in >> which case they can get full bandwidth. >> >> Some designs have simply got 8 lanes per slot all the time. That will >> be slower of course. So if it has the NF200 it should be very good, >> and otherwise it will be speed limited to 8x. Now if you are doing heavy >> calculations with data that fits in the card, it doesn't really matter. >> If your data set is larger than the card can hold and you have to move >> data to the card all the time, the bandwidth could be an issue. That's >> also when the extra memory on a tesla might start to make a difference. >> >> Really serious boards do have enough lanes for 16x on each slot. >> >> The Tyan board I listed has the intel 5520 chipset, which has 36 lanes, >> but since it has two 5520's, each with 36 lanes, it actually has enough >> to run all four slots at 16x all the time. So that is probably going >> to be as fast as you can currently get. The supermicro dual opteron >> board in the machine you mentioned also has dual chipset, which also >> gives it full 16x on all four slots. The Asus P6T7 WS board uses the >> NF200 chips instead. It only has 36 lanes (and of course only one >> CPU socket). > > Of course for really crazy (and expensive) there is this: > http://www.colfax-intl.com/ms_tesla.asp?M=102 > > Dual xeon and up to 8 tesla cards (it uses PCIe switches to share 16 > lanes between pairs of cards). > > Price is rather high when filled with tesla cards and ram and such. > Probably fast though. > > -- > Len Sorensen > -- To UNSUBSCRIBE, email to debian-amd64-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/BANLkTi=pcy1tb+t0nv-yt90agciknmt...@mail.gmail.com