AS3 -- Pulling out all the stops

I finally decided to get some of the good stuff (AS3) and quit using the old Radio Shack thermal grease (though it served me well for years).

I ordered a new P4 1.8A to try my hand at doing a correct HSF installation and a 6g tube of AS3. For starters I figured I'd follow the instructions to the letter. I lapped the heatsink to get all the wax compound off, cleaned the processor and heatsink with alcohol, did an AS3 stain on the heatsink and applied a tiny blob of AS3 to the processor. Then I fitted the heatsink. Not having any previous experience with this compound, I figured I remove the heatsink right away and see how evenly things mate.

Not so good. Right away it was apparent that the processor was going to need some surfacing--the heatspreader edge was digging into the heatsink and looked to be somewhat concave in the center. It looked pretty obvious to me that the AS3 wasn't making good contact in the center at all. The AS3 seems to be much thicker than the Radio Shack thermal grease and may take more force to get it to spread. Anyway, no problem, pull everything apart and lap the processor.

I was rather surprised that I had to do this, but the factory surface on the P4 heatspreader leaves a lot to be desired. So I found me a piece of chip foam to protect the pins and began lapping the chip. I took it down just to the point where the copper started to show through in the center. Interestingly enough, the edges cut down a lot too. The surface originally had an odd shape--high on the edges and center, low everywhere else. Once that was done, I cleaned everything up with alcohol and started over.

This time I stained both the heatsink and the processor heatspreader, then attempted to mate them up. Again, I pulled them apart and inspected the thermal joint. Much better, this time. I could see complete coverage of the compound, though it didn't ooz out the edges. I think this has to do with the viscosity difference between AS3 and the cheap stuff I'm familar with.

I'm going to continue assembling this system and I'll let you know how the temps look. The message I'd like to send home is this:

Regardless of how good the parts are that you purchase, it takes quite a bit of TLC to make everything work like it's supposed to. The best thermal compound in the world is rendered ineffective if the surfaces aren't properly prepped and checked. One other note: If anyone knows how to install the stock HSF on a P4 without moving things all over the place, please advise. As hard as I tried to keep things stable while getting the little clips to lock-in, I still noticed the heatsink moving atop the processor. I don't know for sure if this movement tears-up the thermal joint made when the heatsink first contacts the processor or not, but my gut tells me the less movement the better after the two surfaces touch.

[mookydooky]

Sounds like you're on your way. Good luck with your build!

Originally posted by mookydooky
Sounds like you're on your way. Good luck with your build!

Thank you mookydooky.

Results are in:

For both samples, my system temp was 28C.

Previously, I used the old Radio Shack thermal grease. Temps were 41C idle, 50C full load.

Now with the AS3 I'm at 36C idle, 40C full load. A pretty good improvement--shaved 5C at idle, 10C at load. I'll give the stuff a thumbs up, even though it is a little more tricky to apply and the surfaces must be prepped very carefully.

[Uncle Bob]

You may find that after if 'burns in' the AS III will work even better, whereas the RS 'goop' will degrade over time.

[RandyB]

Originally posted by Uncle Bob
You may find that after if 'burns in' the AS III will work even better, whereas the RS 'goop' will degrade over time.

That has been my experience as well. I always seem to lose another 2 to 4 deg off my idle and load temps a day or two after the initial application, although results are sure to very as to how much temps will drop from sys. to sys. Good job , it looks like your paying attention to detail.

Originally posted by RandyB


That has been my experience as well. I always seem to lose another 2 to 4 deg off my idle and load temps a day or two after the initial application, although results are sure to very as to how much temps will drop from sys. to sys. Good job , it looks like your paying attention to detail.

Thanks RandyB!

I'll watch it for a day or two and see how it looks. Right now it's encoding video while running Folding@Home; everythings looks nice and stable, temps good, power good. I think I have a winner here so far. Hope so anyway, this system is going to be used as my main Internet server. With all the hacker attempts and viruses floating around, the last thing I need is hardware failures to deal with.

Any of you guys know about what speed a stock Intel fan is suppose to run at?

Mine show around 2360 which seems kind of slow.

[Tekime]

I think they usually spin at 2200 to 2800 rpm, IIRC. That would sound about right given your current readings.

Extremely nice and careful job you did by your description of it. I would also agree that AS3 takes a few days to really set in and yield the best temps. Good luck, I hope everything continues running nice and smooth for you