DDR problems with 4 DIMMs?

Bremen

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Mar 22, 2001
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Is it common for motherboards to run ran at slower speeds when all 4 DIMMs are populated? I have an Asus A8R-MX which will only run at 333 when I have all 4 DIMMs filled (4 GB) but if I use 2 DIMMs (2 GB) it will run at the stated 400 speed. I'm not certain but I think it might also have stability issues when using the max ammount of RAM (this isn't a definite though...)
 

Painman

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Feb 27, 2000
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This is a limitation of the CPU, since it incorporates the mem controller. It seems you have an earlier stepping of CPU; E4 stepping and higher (Venice, San Diego, any X2 or Opteron) will not have this limitation, though you may still have to run a 2T command rate for the RAM (a lesser penalty than being stuck at DDR333).
 

Painman

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Feb 27, 2000
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Hrm... the mem controller issue was definitely part of the "improvement" package of the newer steppings over Winchester, etc. If it's still happening with a San Diego CPU, the next step would be to have a look at the motherboard BIOS, which may be making the assumption that the CPU can't handle the increased RAM speed.

ASUS does like to play "nanny", though there is something to be said for a tier 1 mobo maker erring on the side of caution.
 

Bremen

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Mar 22, 2001
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Originally posted by: Painman
ASUS does like to play "nanny", though there is something to be said for a tier 1 mobo maker erring on the side of caution.

Well I bought a low end OEM open box board (hey it was $30 from newegg :0) If I cared about top performance I wouldn't have gotten this board in the first place.
 

Painman

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Feb 27, 2000
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Originally posted by: Bremen
If I cared about top performance I wouldn't have gotten this board in the first place.

It seems that you've got what you paid for then. ;)
 

Blain

Lifer
Oct 9, 1999
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Originally posted by: Bremen
If I cared about top performance I wouldn't have gotten this board in the first place.
Then why worry over DDR400 running @ DDR333?

 

Bill Kunert

Senior member
Oct 9, 1999
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My KN8-SLI defaults to 333 with 4 dimms but I can manually set it to 400 in bios. Not a big deal
 

fire400

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Nov 21, 2005
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check the manual. memory sticks over dimm slot usage applies as far as amount of RAM a stick carries and how you spread them out.

regardless, you're not going to see much a performance increase anyway even if you could get your sticks to hit DDR400 with that processor.

p.s. you're sure your RAM is DDR400, right?
 

Bremen

Senior member
Mar 22, 2001
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Originally posted by: fire400
check the manual. memory sticks over dimm slot usage applies as far as amount of RAM a stick carries and how you spread them out.

Not sure what you're trying to say here.

regardless, you're not going to see much a performance increase anyway even if you could get your sticks to hit DDR400 with that processor.
What you're saying my lowend processor isn't uber133t??? lol, a P3 would have been enough for my needs, but it would actually cost more!

p.s. you're sure your RAM is DDR400, right?
Definitly.