ECC in powermac??
I have been playing around with server dimms for my ppc 7500/G3upgrade (5V modules are quite expensive in Germany). The ones I could test where COMPAQ EDO ECC 5V RAM (64MB). As far as I could find reference to the subject, it is stated that ppc models do not support ECC RAM. My experience: 1. the central notch in the server modules I had has a slightly different position than the key in the ppc memory socket, this can be corrected with a common nail-file. different keying in the sockets can be due to voltage type or buffered-unbuffered modules (see below), however the explanations below do not match my case (central notch was off-key, both module types were 5V). 2. with a Compaq Module, the computer booted allright and seemed to behavee normally, however the ISDN GeoPort Adapter was not recognized any more. switching back to the old memory inmediately corrected the problem. I did not zap the PRAM after inserting the server modules. 3. I did not go further with my experiment because of one main drawback: the hight of the server modules. the case does not close any more, so it is no use in a 7xxx case. tower models or clones might be different. 4. Is someone interested in trading the 3 64MB Modules (Compaq 228469-001) against ppc suitable modules? (write to me) cheers alexander Some technical information I researched on this topic: http://www.shopquadrant.com/TechSupport/MemoryTerms.htm 3.3V vs 5V 3.3V modules are keyed differently from 5V modules. The second notch between pins 40 and 41 on a 168-pin DIMM determines whether module is intended for systems running at 3.3V or 5V. The distance from the notch to the edge of the module will be slightly different, ensuring that a 3.3V module will not fit into a 5V socket and vice versa. Parity Parity is a method for checking the data integrity in memory. Parity FPM or EDO modules can detect single bit errors. To determine whether a module is parity or non-parity, count the total number of memory chips on the module. If the number is divisible by three, then the module is parity. Otherwise the module is non-parity. ECC (Error Correction Code) Like parity, ECC is a method of ensuring data integrity in memory. Unlike parity modules, ECC can detect multiple bit errors and correct single bit errors on the fly without the system even knowing. The drawback is that ECC error check and correction decreases system performance. ECC modules are often used in servers and system where data integrity is of the utmost importance. SDRAM and DDR modules are available with ECC. To determine whether a module is ECC, count the total number of memory chips on the module. If the number is divisible by three, then the module is ECC. Otherwise the module is non-ECC. Buffered FPM and EDO modules may contain buffers that help the system manage large amounts of memory by re-driving the signals through the memory. Buffered modules cannot be mixed with non-buffered ones. In fact, buffered modules are keyed differently than non-buffered modules. The first notch between pins 10 and 11 in a 168-pin DIMM are of slightly difference distance from the edge. Therefore, it is not physically possible to install buffered modules into the memory sockets of systems designed for non-buffered and vice versa. Buffered modules are often used in servers and systems where data integrity is important. ----- Original Message ----- From: "A.Tuazon" <[EMAIL PROTECTED]> To: "PCI PowerMacs" <[EMAIL PROTECTED]> Sent: Wednesday, May 22, 2002 11:07 PM Subject: 7300 RAM question > Yes yes I know this has been a topic a plethora of times but hear me out. > Ok, my question is I just picked up bag full of 32meg rams (16 sticks). The > sticker on each ram stick reads " IBM 32MB 60NS (4MX72) 5.0V ECC " Is it > possible to use this type of RAM in the 7300? The manual only says EDO or > FPM, so I'm not sure if these sticks will work in my 7300. The guy I got > them from assured me they were 168 pin DIMMs. > > > TIA > > > -- > PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... > > Small Dog Electronics http://www.smalldog.com | Refurbished Drives | > -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | > > Support Low End Mac <http://lowendmac.com/lists/support.html> > > PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> > --> AOL users, remove "mailto:"; > Send list messages to: <mailto:[EMAIL PROTECTED]> > To unsubscribe, email: <mailto:[EMAIL PROTECTED]> > For digest mode, email: <mailto:[EMAIL PROTECTED]> > Subscription questions: <mailto:[EMAIL PROTECTED]> > Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> > > Using a Mac? Free email & more at Applelinks! http://www.applelinks.com > > -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
