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So i built a Phenom II Machine a few days ago with a Phenom II 955 C3, prime95 load temps max out @ ~60c (no OC + stock cooling with stock heat paste) and it fails prime95 large FFT's after ~5 minutes passes all other prime95 tests and memtest86. i've tried reseating the HSF twice, checked the cpu voltage it's @ 1.35 Vcore... & ambient is ~26...
 

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i had similar results with my stock cooler, thing was trash.

ps: btw those thermal pads are a disaster.. glued itself to my chip and had to get it off with a isopropyl coated razorblade. had the same problem with my athlon x2 back in the day. they aren't even great at transfering heat

but yeah with the stock cooler i was at 59c 10mins into a blend in prime.. eek
 

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for stock clock you barely need 1.35v, 1.25v should be suffice thou i think it would be fine with 1.2v. large ftt failed could be due to ram issue. frequency & timing of your ram?
 

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Ram is @ 1333Mhz timings are 9-9-9-24
 

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Pavelow, how many fans do you have in your CM690? I have the same case with 7 120mm fans. The top above the cpu and rear fans are exhaust, while the rest are supply. I made sure I had more air entering the case than leaving (positive pressure). Checkout this Sticky by N-Sanity on fans.

Quote:

Originally Posted by ah_khoo View Post
for stock clock you barely need 1.35v, 1.25v should be suffice thou i think it would be fine with 1.2v. large ftt failed could be due to ram issue. frequency & timing of your ram?

Whoa, so I could possibly undervolt my 955 C2? I hadn't thought of doing that. Hmm, I wonder if that would work with the light OC I've got it set at? Currently have it at stock volts (1.35VDC) and x17 multi (3.4GHz) with ram at 1333 @ 1.86VDC. I definitely have got to try that when I get home from work in the morning.

Sorry Pavelow, I didn't mean to jack your thread like that, I'll try to refrain from doing it again. It's just interesting to me, the idea of undervolting a cpu, and for some reason, I never thought of doing that with my 955 C2.
 

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okay, I've got my 955 running @ 1.216v, it seems happy and it gets 54c on P95.... dunno if it's me or not but it feels a bit sluggish after the under v...

UPDATE: got it up to 1.25 it gets to 55.5c on p95 ima leave the volts there

and any ideas about large FFT's
 

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Quote:


Originally Posted by Pavelow
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Ram is @ 1333Mhz timings are 9-9-9-24

exact ram model & rated volt? mind to show the spd table using cpu-z?


Quote:


Originally Posted by LoneWolf3574
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Whoa, so I could possibly undervolt my 955 C2? I hadn't thought of doing that. Hmm, I wonder if that would work with the light OC I've got it set at? Currently have it at stock volts (1.35VDC) and x17 multi (3.4GHz) with ram at 1333 @ 1.86VDC. I definitely have got to try that when I get home from work in the morning.

should be the same for a 3.2GHz (different case for higher clock), if not i'm pretty sure 1.25v is good enough.


Quote:


Originally Posted by Pavelow
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okay, I've got my 955 running @ 1.216v, it seems happy and it gets 54c on P95.... dunno if it's me or not but it feels a bit sluggish after the under v...

UPDATE: got it up to 1.25 it gets to 55.5c on p95 ima leave the volts there

and any ideas about large FFT's

what ya vdimm at the moment?
 

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Discussion Starter #8
Quote:


Originally Posted by ah_khoo
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exact ram model & rated volt? mind to show the spd table using cpu-z?


okay here are the ram specs =>




model is: CMV4GX3M2A1333C9

i appreciate the help
 

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Quote:


Originally Posted by Pavelow
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okay here are the ram specs =>




model is: CMV4GX3M2A1333C9

i appreciate the help


what is the vdimm you're putting now? try either 1.65v or put command rate @ 2t. your imc is @ stock so most probably is the ram that causing failure in prime.
 

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Discussion Starter #10
yeah i thought it might have been the ram, i'll try 1.65v
 

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okay... i tested @ 1.5 vdimm before i changed to 1.65 vdimm to see how long it took to have an error... it didn't...
the only thing that had been changed was the Vcore... (1.25v) so yeh... might have been the memory controller?? dunno.. I'll post back in this thread if i have any more problems.... the help was appreciated
 

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Quote:

Originally Posted by Pavelow View Post
okay... i tested @ 1.5 vdimm before i changed to 1.65 vdimm to see how long it took to have an error... it didn't...
the only thing that had been changed was the Vcore... (1.25v) so yeh... might have been the memory controller?? dunno.. I'll post back in this thread if i have any more problems.... the help was appreciated

hmm... maybe it was pure heat issue. lower volt leads to lower temp hence no failure in prime? congrats... get a better cooler if possible, it's a waste runnin a 955be @ stock...
 

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Discussion Starter #13
haha yeah i've seen pretty high oc's on the 955.. can you recommend any HSF's??
 

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budget for the heatsink? cheap one like coolermaster hyper 212+ performs quite up to my standard (for average oc like 3.8GHz & below) while for high end, you can consider prolimatech megahalems/megashodows, TRUE 120 or even d latest Venomous X. the issue with these high end coolers is you need to get AMD mounting kit which sold separately, meaning that more cost is involved.
 

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the hyper 212+ looks good and i don't plan to go anywhere past 3.8... so I'll probably settle for that.
 

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Quote:


Originally Posted by Pavelow
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the hyper 212+ looks good and i don't plan to go anywhere past 3.8... so I'll probably settle for that.

it comes with 2 pair of fan clips which is good for push-pull config, all you need to do is to buy another 12cm fan, voila... you got yourself a decent cooler...
 

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Discussion Starter #17
cool, thanks for the help
 

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Discussion Starter #18
I'm getting occasional warnings saying that my cpu fan doesn't work properly any ideas?
 

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Is it plugged in? Or could it be a faulty connection. Reading back through your thread, if your fan isn't cooling properly, that could be the source of your bad temps. Can you try to plug it into another socket on your motherboard? or adapt it to your power supply?
 

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Are you using any software to check the fan's speed? Do you have Smart Q-Fan/Automatic fan speed enabled in the bios? Temps are most likely causing your stability problems. 60c is way too hot. Here is what's probably going on:

The stock 955 fan has a thermistor on it (thanks to imadude10 for pointing that out to me!) that regulates the fan speed based on the temp of the air coming through the fan. The problem is that this locks the fan to about half speed, so at 100% in the bios or any software you are running, it's only spinning at about 3k rpm or so. The air inside your case has to reach a pretty ridiculous temp (I think it's 42c) for the fan to run at a useful speed. It's even worse if you have any kind of smart fan enabled, because it will only allow the fan to run at "full speed" (in our case, half speed) when your chip is already way too hot.

A way to get around this is to wrap a copper wire around the two thermistor wires to short it out or solder it in the same way. It's pretty small so it's hard to do. I decided just to order a new cooler.

And they're right, that stock paste sucks under load. Some AS5 would go a long way.
 
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