Gigabyte 965P-DS3 rev 3.3 and Corsair XMS2 OC questions

Hi all,

My PC won't post after I tried setting +0.5Vdimm to my DDR2. I had to clear CMOS for my PC to work again.

My setup at that time was:

FSB: 395Mhz
CPu multiplier: 8x (QX6700)
Vdimm: +0.5
Vcore: 1.375V
Ram Multiplier: 2.5
BIOS: F10
FSB and mch: both +0.1V

After that, it seems that I can't run my FSB at 395Mhz. When i tried to set 395Mhz, it will only detect as 394Mhz. Did i screw up anything?

What causes my PC not being able to POST when i changed my settings? Is it the RAM speed too high? Or my Corsair RAM confirm not able to accept +0.5V? Or Gigabyte motherboard is restricting my RAM Vdimm to be less than +0.5V?

I'm having problem getting my FSB past 400Mhz...but probably that's because i'm setting *8 multiplier and my processor cannot handle too high speed...

Will try to lower my CPU multiplier to *7 and then try increasing my FSB.

Appreciate inputs here: eg. RAM ratio always 1:1 and 2.5 ratio is not recommended. Or never put Vdimm at +0.5?

Thanks!
5 answers Last reply
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  1. ummmm..........going vDIMM +0.5v and not POSTing? Yeah, that's your problem right there.

    You got a bunch of problems........

    -RAM should be running at 2.0, not 2.5.
    -vDIMM should not be +0.5 for XMS, that's way too high!
    -395 FSB might be an OC wall, strap change at 400 FSB?
    -vCORE probably has to be higher, at least 1.400v

    First thing, fix your RAM multiplier. Then drop vDIMM before you burn out the chips. Then start increasing vCORE.

    GO SLOW! Keep up the direction you're going and you are seriously gonna screw the pooch there bud.
  2. thanks bro... the moment i can't POST...I cleared the CMOS and revert back to +0.4 for Vdimm... well, should i lower it even further?

    I'm planning to increase more on FSB while maintaining my CPU speed at 3.2Ghz (reduce multiplier for CPU to keep up with increase in FSB)...

    So end of the day, i am targeting my RAM to run around 900Mhz for my Corsair XMS2... let me know if +0.3V or +0.4V is ok if you have experince on this...else, i'll be slowly trying this... ;)

    i'm not expecting 395 to be FSB wall though cause i've seen lots of DS3 boards easily going way above 400Mhz FSB...
  3. Well, no offense but you're kinda going backwards...........you're suppposed to start low and move high......with FSB, voltages, etc. Then you push higher, and when you get instability you generally raise voltages a notch. Then stress test and push higher. And on and on.....

    You're going to the top and backing down until you find a combination that works. That isn't the wisest move for your chip.....not to mention it may take forever to find the right combinations like that.

    And yes the DS3 boards go over 400....mine is currently over 450 ;) It's not the board....it's the voltages and RAM multiplier, and similar factors in combination that sound like the culprit. Usually people have volts too low....you have them too high. RAM should start off at stock, then eventually +0.1v......not start at +0.5 or +0.4v. And that XMS isn't D9 Micron RAM....so it'll only overclock so much until it won't go any further, no matter how much volts you give it.

    Start low, go higher. Up, test, up....volts up a notch, test, up, test....and so forth. I know it's a pain and can be time consuming, but that's how it's done, and that's how you don't blow out your CPU or RAM.
  4. ok... thanks and noted!
  5. Quote:
    My PC won't post after I tried setting +0.5Vdimm to my DDR2. I had to clear CMOS for my PC to work again.

    The first thought that came to my mind is that you burned out your RAM by over-volting it. If that did not happen, then I think you are one lucky fellow.

    No offense, but why on earth would you think your RAM could handle running at ~DDR2-1000 (2.5*400MHz FSB if I'm remembering correctly how the DS3 memory ratio settings work). Are you using DDR2-1000 or better RAM? If so, then according to Corsair's specs +0.4/2.2v should be enough ... no? You should not have to overvolt by +0.5 to 2.3v to get it to work. (And if it isn't DDR2-1000 or better, it sounds like you may be trying to push it further than it can go).

    A related question is why on earth you'd want to push your RAM so hard in the first place. Why the 2.5 ratio?? :? My understanding is that the reason most folks spend the big bucks on high speed memory is to allow them to jack up the FSB speed to 400-500MHz while keeping a 1:1 RAM ratio. There's just not that much point to forcing your memory to run faster than the FSB asynchronously. The performance gain is typically at best only a few percent ... not something you're likely to notice.

    If you haven't already, I suggest you drop everything back to the stock/default settings and just make sure you system still works. If it does, then follow the advice others have given you already and move slowly ... and carefully! ... up from there.

    -john, the ostensibly clueless redundant legacy-in-transition dinosaur
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