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Ash M
01-01-2005, 06:38 PM
Hey,

I've just built up a system with a Semperon 2500+ processor on it. Its running with the stock fan, and some aftermarket thermal grease.

However, it is starting to bug me... I am getting alarms that the temperature is too hot. I am sure the fan is installed correctly, yet it still happens.

The bios reports the temperature (after its been on for a few ours and after being at moderate load at 63 degrees celcius, which I would consider a bloody hot chip. My system is set to auto-shutdown when the temp hits 70...

The fans are all installed and working correctly, as far as I can see...

Any ideas... what do your semperons run at?

Ash

~sy~
01-01-2005, 07:38 PM
That is awfully hot. I think your Bio might be stuffed up, although I don't know. From what I hear, AMD are pretty good with their temperature control these days.

What board are you using?

Otherwise, just do what I do and go Intel :p

eat soap
01-01-2005, 07:46 PM
What mobo are you using? If you haven't flashed it with the latest bios you should do so. Make absolutly sure you applied the thermal grease properly. You might want to re apply the grease.

Terry Porritt
01-01-2005, 07:55 PM
No, not really awfully hot. I'd say that could be about right. The Semperaon is rated at 90 deg C max, so you are still ok.

Just read the last page of my cpu temperature measurement results:

http://pressf1.pcworld.co.nz/showthread.php?t=52362&page=3&pp=10

Your BIOS is giving the temperature calculated from the inbuilt thermal diode.

This will be at a higher temperature than at the face of die/heatsink.

If the stock AMD heatsink has a thermal resistance of 0.5degC/Watt, and the semperon is running at its maximum of 62 Watts, then the temperature rise will be ~30deg C at the interface.
If the ambient temperature is 25 deg C, then you would expect 55deg at the die/heatsink, and about 60deg C at the thermal diode.

If your stock AMD heatsink is as badly out of flat as mine was for the XP2400+, then expect another 5deg C rise.

A lot will depend on case ventillation. Best is a 120mm fan in the side blowing directly onto the cpu fan.

Ash M
01-01-2005, 07:58 PM
Cheers Terry & others... Thats seems to be the consensus from more googling as well, but it can't hurt to purchase a case fan.

Ash



No, not really awfully hot. I'd say that could be about right. The Semperaon is rated at 90 deg C max, so you are still ok.

Just read the last page of my cpu temperature measurement results:

http://pressf1.pcworld.co.nz/showthread.php?t=52362&page=3&pp=10

Your BIOS is giving the temperature calculated from the inbuilt thermal diode.

This will be at a higher temperature than at the face of die/heatsink.

If the stock AMD heatsink has a thermal resistance of 0.5degC/Watt, and the semperon is running at its maximum of 62 Watts, then the temperature rise will be ~30deg C at the interface.
If the ambient temperature is 25 deg C, then you would expect 55deg at the die/heatsink, and about 60deg C at the thermal diode.

If your stock AMD heatsink is as badly out of flat as mine was for the XP2400+, then expect another 5deg C rise.

A lot will depend on case ventillation. Best is a 120mm fan in the side blowing directly onto the cpu fan.

Metla
01-01-2005, 08:02 PM
Ensure your fan is orintated correctly,The heatsink will have a step on the bottom surface which must be alligned with the offset on the cpu socket.

george12
01-01-2005, 08:06 PM
I think it would be running more than 63 deg if he had the HSF backwards - it wouldn't line up with the CPU die if that was the case, so he might as well not have a heatsink.

How much thermal grease did you use, it could have been too much (a common mistake).

Terry Porritt
01-01-2005, 08:16 PM
You know the die area on those "unlidded" cpus is very small, 11.4mm x7.4mm, it's a tiny area to get rid of 60 odd watts.

Thats why it is important that the heatsink surface is as flat and as smooth as possible. What comes after by way of size of heatsink and fins and fan speed is almost of secondary importance. Making the heatsink bigger is a 'law of diminishing returns'.

A big heavy heatsink with a tower case and vertical motherboard is putting a big cantilever moment onto the cpu trying to fight the spring clip force.

If your heatsink has a screwed on plated copper base, take it off carefully and see how the grease has been applied.
On mine only half the area was covered because of out of flatness.

Also the plating is harder than the copper underneath, so the die does not bed into the copper as it does when the plating is removed. I may on mine try annealing the copper base to make it softer, that will mean another hour or so lapping it again.

If you can get hold of a piece of thick float/plate glass, like 25mm thick, use it as a flat surface to rub down the heatsink surfaces using wet and dry abrasive paper, starting with something like 320 grit and working progressively up to 2000.

You should be able to get 5 deg less by spending some time ( actually a whole heap of time) working on the heatsink.

Metla
01-01-2005, 08:20 PM
I think it would be running more than 63 deg if he had the HSF backwards - it wouldn't line up with the CPU die if that was the case, so he might as well not have a heatsink.

How much thermal grease did you use, it could have been too much (a common mistake).


George,Grab a socket A cpu and heatsink and have a play, Then let the enlightenment wash over you.

george12
01-01-2005, 08:46 PM
Yup, done.

And it looks strikingly obvious, and is hard to clip on that way.

Having said that, I have seen people do it myself.

Had a guy in once with an AthlonXP 2800+, running at like 85 degrees, and he had done just that.

So I will be quiet now...

Ash M
01-01-2005, 09:22 PM
I think it would be running more than 63 deg if he had the HSF backwards - it wouldn't line up with the CPU die if that was the case, so he might as well not have a heatsink.

How much thermal grease did you use, it could have been too much (a common mistake).

Yeah, i think I put on maybe a little too much, cleared off and re-applied with an old credit card, and temp has gone back to about 56 or so and seems to be stagnant there.