DLorimer Posted November 11, 2004 Share Posted November 11, 2004 I have a SuperMicro P6DBU mb with the Intel 440BX chipset. It was originally spec'd with pc100 SDRAM, max of 1 gig total in 4 modules of 256M ECC registered. I have recently tried Kingston pc133 256M ECC registered modules. They do not function at all, one two, three, or four modules (I tried all). Board just beeps on boot up. The Kingston modules have a total of 9 memory ICs. I was told by SuperMicro Tech support to look for modules with 16 to 18 ICs, as these are "lower density" and may work better. The board does function with (2) older OEM Micron pc100 256M modules, non-registered. Will the Corsair 256M ECC Registered pc133 modules, part number CM766S256-133 work in the BX mb? I found another Corsair 256M ECC registered part being sold by PCProgress, listed under pc100, as CM744S256-BX, supposedly for BX mbs. But this part is not listed on the Corsair website and does not come back if I search the part number. Which of these will work? The later part is almost double the price, so I would prefer the former. Is the latter part out of production? Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted November 11, 2004 Corsair Employees Share Posted November 11, 2004 Many of the server MB's based on this chipset would support by 4 or By 8 memory IC's just not together. But I am not sure if this MB will support By 4 memory, it should. But you may not be able to mix the other memory you have. CM766S256-133 Made with By 4 Memory IC's CM744S256-BX Are made with By 8 Memory IC's Link to comment Share on other sites More sharing options...
DLorimer Posted November 11, 2004 Author Share Posted November 11, 2004 Can you explain what you mean by "by 4" and "by 8"? Does this refer to the density on the module? The Kingston memory, which did not function, is part no. KVR133X72RC3L/256. Is this "by 4" memory? I am not concerned about compatibility with the currently functioning memory. Since its un-registered, the maximum that can be used is 512M anyway. So to ugrade to 1G, I must replace all modules with registered versions, and the older stuff cannot be mixed with the new. Thanks for the links, but my BX Supermicro mb is not listed (P6DBU). I also have a P6DGU, and this chipset is much more tolerant of the pc133 memory. The Kingston part works fine in this mb. Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted November 11, 2004 Corsair Employees Share Posted November 11, 2004 By 4 or By 8 would refer to the organization of the memory IC's. 32M = The density of the IC X 4 = The Data Bits per IC and the number of IC's multiplied by this has to add up to 64 Bits. So with a Module made with By 4 IC's would have to have 16 IC's for the module to work in any system. And 16(# of IC's) X 32M = 512 Meg total module size. 32M The density of the IC X 8 = Bits times 8 = 64 Bits so you can make a module with 8 IC's but that would be 256 Meg for 512 Meg you would need 8 more or 16 total and the modules would be double sided. 32M The density of the IC X 16 = Bits times 4 = 64 so you can make a module with 4 IC's on one module, but the size of the modules would be 128 Meg The By 4,8, or 16 will need to add up to 64 Bits by the number of IC's to make a working module. With ECC you would add 8 Bits or it would need to add up to 72 Bits instead of 64. Link to comment Share on other sites More sharing options...
DLorimer Posted November 12, 2004 Author Share Posted November 12, 2004 So, let me see if I have this right. If its x4 memory, there would be 16 IC memory chips/module for non-ECC, 18 chips/module for ECC. If its x8, then there would be 8 chips/module, 9 for ECC, and if its x16, then there would be 4 chips/module non-ECC, but 4.5? for ECC? This rule applies irrespective of the total memory, right? So, the original Micron memory is x4, and the Kingston that didn't work is x8. BTW, the Kingston was not mixed with the other memory. It did not run with even one module in Bank 0, and no other memory installed. I guess I need x4. Does Crucial still make any x4 256M registered memory? Thanks for the previous info, its been very helpful. Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted November 12, 2004 Corsair Employees Share Posted November 12, 2004 So, let me see if I have this right. If its x4 memory, there would be 16 IC memory chips/module for non-ECC, 18 chips/module for ECC. A: No By 4 IC's would always be in a buffered module. With other makers I would not be able to help you; you would need to ask them what they are selling you. In addition, you can not mix By 4 and By 8 memory in the same system. And some chipsets may support both By 4 and By 8, but it's up to the MB maker to implement support, as it may require a slightly different MB layout to support both. Link to comment Share on other sites More sharing options...
DLorimer Posted November 12, 2004 Author Share Posted November 12, 2004 By your previous description, I have "by 4" memory (16 chips/module), but I know its not registered or buffered. It also does not make sense to me that the older Corsair part (with the -BX suffix) is a "by 8" part, with fewer ICs/module; and that the current part CM766S256-133 is a "by 4" part with more ICs/module. Aren't the current technology parts tending to be "by 8" and "by 16" parts because the memory ICs are larger in capacity? Unfortunately, I don't think I am any closer to determining what Corsair memory will work in my motherboard. One other observation. I placed 1 G of 256M modules in my P6DGU board and observed the boot up screen. Four of the denser 256M "by 8" Kingston parts, when booted up in the P6DGU mb, indicates 256M in each of banks 0, 2, 4, and 6. The Micron memory, indicates 128M in each of banks 0, 1, 2, 3, 4, 5, 6, and 7. The Micron memory also indicates 128M in banks 0, 1, 2, and 3 when booted up in the P6DBU. Does this have anything to do with the problem? It seems that my BX board wants memory that is distributed, and no higher than 128M/bank. How do I determine which Corsair modules meet this requirement? Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted November 12, 2004 Corsair Employees Share Posted November 12, 2004 No you can not go by the # of chips, which is a limitation of one configuration of memory IC's not a defacto law for all modules. What is the part# of your module? CM766S256-133 is a registered ECC module made with By 4 memory IC's. The MB P6DGU is based on Intel 440 GX chipset and you should be using that module, but you would not be able to mix By 4 and By 8 memory in that MB. If the memory you had in the system was By 8 then you may have to reset or clear the bios with our modules (Only) installed for the chipset to change and be able to see By 4 IC's. Link to comment Share on other sites More sharing options...
DLorimer Posted November 13, 2004 Author Share Posted November 13, 2004 Please re-read my original post. The memory I need is for the 440BX (P6DBU)chipset, not the 440GX (P6DGU) chipset. Lets forget all the "by 4" and "by 8" discussion. I don't plan to mix memory from different sources. I just need a part number for a compatible part that Crucial will certify works with the P6DBU mb. Assume that its the only part in the system and that there are four modules of 256M each. Your memory compatibility data link does not list the P6DBU mb, only the DGU part. So it is still unclear that the suggested part number CM766S256-133 will work with the BX chipset (or the P6DBU). So, does Crucial have a part that works, or not? Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted November 15, 2004 Corsair Employees Share Posted November 15, 2004 I am sorry; we do not test with or for Crucial memory. If that is what you want to use I would suggest you ask them. Sorry, but this is Corsair! Our part# that would work with an Intel BX440 chipset would be VS256MB133 with no "A" in the part#. Link to comment Share on other sites More sharing options...
DLorimer Posted November 16, 2004 Author Share Posted November 16, 2004 Sorry. Of course I meant Corsair, not Crucial. Thanks for the recomendation. Link to comment Share on other sites More sharing options...
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