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Phenom II 940 over 76C on Prime but 58C real world

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July 11, 2010 11:22:21 PM

OK so this is another "Phenom hot" thread but I have more specific information and I think the results are interesting.

system:
Phenom II 940, model 4 stepping 2 Rev RB-C2, 3014 MHz, 1.36V (stock)
Thermaltake V1 cooler with included silicone grease
Gigabyte GA-MA770-DS3 rev 1, F8F bios
Geil PC2-6400 (800 MHz) 2 gb x2, unganged
GT 240 video - running Folding at Home 100% load 24/7
500W power supply - rails are solid.
I am NOT OVERCLOCKING anything.

I started running with the stock cooler. It worked but was darn loud - screaming like a banshee at 6 krpm running Rosetta at Home (RAH) 24/7. I couldn't stand it. I got the Thermaltake V1 at Fry's. Now I know you will tell me that's not a great cooler and that stock thermal paste sucks and I suck at putting it on and my case has bad cooling BUT all aspects are at least "OK". Really, I have decent cooling.

Idle 44C (with GPU 100% load on FAH). That's a pretty typical result.
Prime95 25.11, 4 threads 8k FFT size - hit 70C in 7 minutes. I shut it off at 76C and it was still creeping up! :ouch:  The CPU fan does max out at 2052 rpm at 62C like it should. Prime did not report any errors. And I'm NOT OVERCLOCKING.

BUT any real world app is OK. I ran RAH all night at 100% CPU load and it never went over 58C. Cinebench 11.5 CPU three times in a row 59C max. Even Prime at 1024k FFT size is steady at 64C at 30 minutes.

Prime 8k FFT stays in cache while 1024k and all real apps use RAM. Memory speed at 800 MHz is a major bottleneck, which is "good" because that stops it from smoking. I could increase the memory speed and improve cooling but I don't want to mess with it any more.

For anybody that has a big overclock, I'm curious what your Prime 8k and 1024k temps are. Careful, 8K might surprise you.
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July 11, 2010 11:54:27 PM

http://www.frostytech.com/articleview.cfm?articleid=229...

its not that bad of a cooler, the thermal paste must be dropped in a small dab then spread by the weight of the cooler, prime 95 does not represent any real world stress it stresses the cpu to the farthest possible limits, i use wprime to represent real world stress, what does it max under wprime?
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July 11, 2010 11:54:45 PM

You really need to make sure you didn't use enough thermal paste & you mounted the heatsink correctly. The Phenom II's max is 62°C, you should be running at 55°C full load. I suggest you try undervolting it, or buying a better cooler.
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July 12, 2010 1:15:49 AM

2137544,2,344447 said:
...the thermal paste must be dropped in a small dab then spread by the weight of the cooler[\quotemsg]

Really? It must? The way i've always done it is to put a dab on the cpu "heatshield", then use a bank card (or something to that effect) to make an even layer that covers the shield, then same for surface of the heatsink. Then mash them together. Never had any problems with heat doing it this way.
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a b à CPUs
July 12, 2010 3:49:05 AM

^sometimes doing that there can be too much thermal paste between the cpu and heatsink
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July 13, 2010 5:48:34 AM

Thanks for the feedback. wprime - 1024M was 57C starting from idle, 440 seconds. Hit 60C overnight on Rosetta

I got my volt meter/ thermocouple and IR gun out.
room 23C
outside case exhaust fan 33C
Inside I found the hottest spots were the SB at 50C and the VRM MOSFETs at about 65C. So getting some cooling for the VRMs or undervolting might help. This isn't a fancy board - basic NB and SB heatsinks and nothing on VRMs. Maybe I'll try the paste again but I doubt I can do better.
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a c 102 à CPUs
July 13, 2010 6:20:29 AM

I am no expert but it looks to me running the GPU at 100% is heating the case too high and causing the problem, try stopping it for 10 mins and see.
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July 15, 2010 5:53:28 AM

simon12 said:
I am no expert but it looks to me running the GPU at 100% is heating the case too high and causing the problem, try stopping it for 10 mins and see.


No difference at all. GT 240 is fairly low power. I guess it's 1/2 the 8800GT it replaced.

I did redo the thermal paste with ceramic instead of just silicone and it helped a couple degrees. The CoolerMaster technique was slick. They give you a piece of thick tape with a square cutout and a plastic piece like a credit card. You put the tape on the cooler, run a line of paste on one edge of the cutout and squeegee the paste across with the credit card to fill the square. Pull the tape off and install. Nice even coat. Naturally I used the extra 2 deg C for a small overclock. :p  It's always under 62 so I'm not concerned.

This thing overclocks great. I just bumped the bus from 200 to 245 without changing anything else and it's rock solid BUT runs way too hot under load. I've got my eye on the 95W 6 core Phenom for the next build. That should be very nice. :D 
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