975XBX2 and P5E3 4 DIMM problems....

[mnemonick]

I have been having the worst time with this... I have 10 of these boards running, some are over clocked, and some are not. I had one board with an X6800 and 4 1GB Kingston 667 DIMMs running fine for over a year, not OCed. I replace the X6800 with a Duo E6750 no post. I goto maintenance mode, no post. I replace vid card, no post. I replace the WHOLE MB with a brand new one, No post! I take out 2 DIMMS and posts fine... I replace the 2 remaining dimms with the 2 i took out, posts fine... I put all 4 back in, no post. I even turned the ram volts up to 2.00 while on 2 dimms, and re-booted with 4, no post. I have had this problem more than once depending on the CPU believe it or not, and also with the latest bios. I think the E6750 is one of my problem Childs with a 4 DIMM set-up. As I said I ran an X6800 for a full year with no problem at ALL. I also have a P5E3 having the exact same issue with DDR3 ram that was RECOMMENDED by ASUS, OCZ Plat 1333, 2 sticks post fine, 4 sticks no post, and either set works fine by themselves. I cannot believe that in today’s motherboards they cannot figure out how to use ALL 4 SLOTS correctly. All of these were non OC set-ups.

Funny thing is, I have the BX2 OCed with the E6750 to 3.1 Ghz and 677 ram to 751 on AIR, but ONLY 2 DIMMs.

[Gunnz Akimbo]

its something to do with powering on with 4 dimms.
update the bios (with 2 dimms) then turn it off, reset the cmos without the power cable in the psu, and leave it unplugged for a while alltogether.

before i even installled my xbx2, i reset the cmos and took out the battery.

oh, anyway the point is, ive had 4 corsair value ram DDR2-533 sticks in it since i bought it in april, and now they are oc to ddr2-333.

[mnemonick]

I have the bios update, and have cleared the CMOS. It was the different CPU/RAM combo. THe E6750 will not power up with 4 DIMMs but the X6800 will, same MB, fully updated BIOS, and i tried ALL bios resets. it WILL NOT BOOT the E6750 with 4 DIMMs

[gtj]

If you can do it safely, increase the vMCH as well. With 4 sticks it's doing more work.

[JohnZS]

Hi
I have a similar problem with my ASUS P5E3
I just cannot get my P5E3 stable @1333Mhz with 4x1024GB Patriot 1600LLK (2 identical Kits) CL7, My CPU is a QX9650 which has a native 1333Mhz bus (same as your E6750) and I am using the latest BIOS (0703) as well.

gtj what would you say is a safe voltage to raise my NorthBridge to?
Say 1.35 or 1.4V?

Thanks

John

[gtj]

1.35 or 1.4 is OK if you have some form of active cooling. I wouldn't try it with just the stock heatsink. Even a small fan would be good. Having said that, I doubt very much you'll need that much voltage at 1333MHz. 4 sticks is more stress though so maybe a notch or 2 will help.

The X38 is very touchy. A one step voltage change can be the difference between perfectly stable and not, and overvolting is just as bad as undervolting. It's got to be just right; you can't just give it "an extra boost for stability". Same for the vDIMM. It took me a while to dial in the correct settings on my BoneTrail. The easiest way I found is to run Memtest 1.70 test 7 after each change. It's the most stressful of all the Memtest tests.