What are average temps with a 72W peltier and P3 (air cooled)?

I've been out of the forums for a few weeks while I upgraded my motherboard's temp monitoring abilities (Abit BX6 r2 that required the cpu diode fix). I now have real thermal diode temps and they were very interesting.

I have a 72watt peltier and 3/8" copper coldplate all attached to a GlobalWin VOS32. I spent a great deal of time modifying my HSF to allow me to use screws for mounting to the cpu (much tighter to the CPU die). Anyway, the temps are now as follows:

Old (without peltier)
CPU Speed 868Mhz (highest stable possible)
Ambient temp 27C
CPU Idle Temp 35C
CPU Full Load 42C

New (with peltier)
CPU Speed 902Mhz (highest stable possible)
Ambient temp 28C
CPU Idle Temp 18C
CPU Full Load 26C

So there you have it. I figured I'd be getting much lower temps than this, but they still manage to be less than ambient at full load.

I am curious though-Should I follow the same rule for thermal paste on the peltier as I would for the CPU core? I always use a very thin layer of paste on the CPU and I did the same thing on the peltier coldplate surfaces. It occured to me that a thicker layer might be more beneficial, given the less that perfectly flat surface of the ceramic peltier plates. If anyone has any suggestions, I'd love to hear them.

Just an update, I did some testing today and have some new info to post.

I decided to experiment with lower settings, both frequency and voltage, to determine the lowest possible temps from the thermal diode. All you people who have P3/Peltier experience let me know if this looks right:

P3 @ 466Mhz (P3 700@ 66Mhz FSB)
Core @ 1.5 volts (!)

My ambient temps didn't change at all but my idle temps dropped to 1C. At first glance this sounds great but according to my best guestimate, the total wattage of the CPU should be around 14watts for these settings. Correct me if I'm wrong, but shouldn't a 72watt peltier get better results than this?

Bear in mind that I have everything clamped down tight, with excellent insulation on the front and back of my SECC2 cartridge. As always, any suggestions are greatly appreciated.

You could lap the VOS 32, I´m using one on my slot A Athlon an the base was not very smooth..I could easily feel machine Marks on it. I got a 6 degrees temp drop after lapping..you should try this also if you haven´t yet.

Forgot to mention that I'd already done that. I lapped the cold plate as well. And the CPU core is lapped too. I'm not sure the last one accomplished much. Maybe a 1C drop.

Bump

Um, Bump?...

!

And the CPU core is lapped too

Click to expand...

how do u lap the core of a cpu

Very carefully!

Seriously, I don't know that I'd recommend it but here's how I did mine:

I wrapped the cpu in electrical tape to avoid the possibility of getting dust on the parts and lightly sanded the core with 600 wet sandpaper on a pane of glass. I sanded the core till the blue finish was gone.

I'll add that I wouldn't have done this had it not been for pattern of thermal grease the I kept seeing on the core. It was obvious that the core was not contacting the heatsing over about 25% of the surface. I say not contacting, but what I mean is not as tightly as the other 75%. After the procedure it appeared to be a better contact. Again, I only saw temp decreases of about 1 degree celsius, so the value of this is debatable. Hope that helps!

And another bump...

Here a bump, there a bump...

You haven't mentioned condensation. Seen any?

Glad you asked! Actually I took extra care to make sure everything was well insulated and I haven't seen any evidence of condensation.

I do believe I've figured out the problem with my setup though. And also the remedy!

There seems to be an issue with the way I clamped the peltier and coldplate to my heatsink. I read a few reviews that recommended the use of super glue. I have to say that I don't think this is a good idea with the use of a peltier. Mostly because of the amount of time it takes to position the elements. By the time they're set, the glue has hardened. That seems to be the case with my setup-the glue hardened and the surfaces of the parts where not tight enough to allow for a good heat transfer.

The way the setup is running now is showing a marked improvement. My idle temps are now at 9C!

Thanks for the posts and feel free to add questions or comments.

Is the sys in your sig the one you have the pelt on? My interest in all this is because I thinking about putting a pelt under my swiftech. Something like a 85 watt.

I've tried to post this 3 times now! There must be some issue with the server or something. Every time I try to post, I get a page not found error. So here goes nothing.

The sig is my current system with the peltier. I would recommend going with similar setup with one word of caution. If you are trying to go air cooled on a socket 370 rig, I would worry about the heatsink's physical ability to dissipate that much heat.

Duplicate post.

This was a duplicate.

The only reason mine works as well as it does, (which isn't all that great) in my opinion at least, is the sheer size of this heatsink. I'm getting about 45 degrees C on the fins of my sink, which would suggest it's close to saturation (it may have a few more watts it could deal with but that seems a bit hot for the fins). I'm not sure you'd get that with a smaller socket sink. The fact that yours is Swiftech might help though. I'd probably still go with a 72 watt just to be on the safe side. Your call though. I'd be interested to see your results if you went with the larger one. Let me know if you need any more resources or suggestions.

Sorry there where so many posts on that. It was one large post but it wouldn't allow me to update until I cut it up into smaller chunks. Hope it all makes sense.

Thats one way to boost your posts score

Do you think you can post some pics of this beast?