Volt-mod to make memory stable? No option to boost in BIOS.

Hey everyone, I have an old version of the Intel d875pbz board. It doesn't have the option to boost memory voltage in the BIOS. It is static at 2.5v

I've had 2 Geil ultra 400 512's (dual channel) running in there for 6 years with no problems. I recently installed an additional 2 256Mb versions of the same model. They are rated at 2-6-3-3 for 2.55v to 2.95v. Which leaves me 0.05 below the recommended voltage.

I ran memtest86 for 6 and a half hours and got 2 errors on test 5. From my research, this seems to indicate a voltage/timing issue. This wasn't an issue until I installed the two new smaller modules, so I think my motherboard is having trouble supplying enough voltage with 4 sticks installed. EDIT: The two errors occured on the 0 and the 3 DIMM slots

(I've also installed a new power hungry graphics card, but I don't think that would cause trouble when running memtest from a bootable floppy)

So my question is, could anybody help me do a volt-mod to my board? I think just a .05 to .1v increase would be enough to make these work fine.

I have no idea where I would draw with the pencil or place a resistor.

Here are links to a schematic and a picture of my board.

ftp://download.intel.com/design/chipsets/schematics/25281202.pdf (I had to "save link as" with this pdf)

I just moved the sticks to different channels, hoping that will fix things, and will run memtest again while I'm at work tonight. If that doesn't work, I hope I can do a volt mod so I can keep the factory timings. EDIT: Ran a short memtest repeating test 5, got errors on slots 0 and 3 again.

Any help or suggestions would be appreciated.
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More about volt make memory stable option boost bios
  1. AFAIK there are no mods to increase RAM voltage.
  2. There are many posts on the internet explaining how to do it on various motherboards, just not this one.

    Also, I edited my original post to show that I'm still getting the errors after switching channels.
  3. Ok, I changed my timings to 2.5--7-4-4, ran test 5 repeatedly for 7 hours, and got 0 errors. This is definitely a voltage issue.

    So I'd really like to get the super fast factory timings on these, and all I need is a ~.05V boost.

    Could anybody tell me if this is the chip I need to v-mod? If so, which pins should I connect with a pencil? This is from page 76 on the schematic.

  4. After looking at some graphics volt mod faq's, evidently I need to connect the fb and gnd. I'll use a pencil and draw lines till I get something between 2.55 and 2.6.

    Is there anything I'm leaving out here?
  5. Well, I ended up shading in the first resistor connected to the FB. According to most faq's this is the one to shade. The voltage reading on my RAM went up .05v.

    I ran memtest #5 last night on the factory timings (2-3-3-6) and got 0 errors in over 200 tests!

    I guess raising memory voltage has the potential to wear on the mobo, but this was a really small increase, so I think I'm in the clear.
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