Necessary to repaste processor?

gregrocker · 16 Mar 2012

Took out to carport a 7 year old Vista machine to blow out dust and install a case fan. Trying to get the CPU fan off to blow out heat sink and both came off exposing processor which still had wet paste. Hadn't planned on repasting processor so cleaned heatsink and replaced, blew out dust, installed case fan and reinstalled. Temps dropped from 40's to low 30's.

Do I need to plan to repaste since it hasn't been done and came apart. I'm asking because I'm not sure if the answer is absolute or negotiable.

Thanks.

TVeblen · 16 Mar 2012

Not sure I understand completely, but in general you need to have some paste (or "thermal compound") between the processor and heatsink - always.

If you are saying that the old paste was still "fresh", meaning it was malleable (spreadable), then sure, just reinstall with the old paste.

If the old paste was dried out and not malleable then you would then need to scrape off the old residue and reapply new paste.

If the paste is old and is still malleable them it was very good paste to begin with!

gregrocker · 16 Mar 2012

Must be, since it is at least as old as the machine which is 7-8 years, and still looked damp like toothpaste.

After running a few hours it's now up to low 40's on both cores. For an Athlon x64 4000+ Brisbane I found Maximum CPU Temperatures suggested 78c.. Any suggestion for maximum to repaste? Maybe 55c?

I had heard that once you peel the heat sink off it must always be re-pasted and wanted to double check that with someone I trust. Thanks.

DavidE · 16 Mar 2012

I've always read that you should clean and apply new paste any time a heat sink is installed.

A few times I have not applied new paste when re-installing a heat sink, and it has never caused any problems for me.

I'd say just keep an eye on temps for a few days and make sure they look ok.

I don't see why the max temp would be different if it's new paste or not.

TVeblen · 16 Mar 2012

I would think that when you are approaching say, 75% to 80% of the maximum recommended temp then it would require attention. But it depends on what you are doing. If it is hitting high temps under stress then it is grain of salt time. If it hits high temps at idle then that would be cause for concern.

The function of thermal compound is to fill the microscopic hills and valleys that actually make up the seemingly smooth surface of metal components. This fills the air spaces that actually insulates the heat transfer between components. The application only needs to be a very thin layer. A common mistake is to apply too much compound. You want some metal to metal contact with the compound filling the voids between.

Some people get real religious about applying thermal compound. But if you understand the mechanical concept then you can reasonably avoid unnecessary fuss and labor!

gregrocker · 16 Mar 2012

I think the temps are 10c lower due to blowing out significant dust and adding a case fan. I'm not worried about the temps now but will watch them on this machine going forward as I do all of our old machines. It's easy to have CoreTemp start up in SysTray.

linnemeyerhere · 16 Mar 2012

Greg, I just pulled apart a freshly bounded Zalman cooler set up for only a few weeks and afterwards I just added a small dab of fresh paste and installed my Corsairs H50 plate. I understand the material in your 6-7 year old system might seem viscous but I would always recommend cleaning and applying fresh to any system that has been running for more then 6 months. But just as tests have found that mayonnaise and other greases can work just as well as exotic compounds this material is really only filling the smallest of gaps and as long as the two surfaces are in close proximity you will get a good if not perfect thermal exchange.

gregrocker · 16 Mar 2012

Thanks, guys.

What temps do you like to see for your processors at idle and under load?

Is 36-46 with light internet browsing considered cool?

mickey megabyte · 16 Mar 2012

well that's quite a wide range, greg.

the important data is temperature under load.

a bit more paste can't hurt (after removing residue) - if you've got the time, inclination, and the paste. :)

gregrocker · 16 Mar 2012

Is Arctic Silver still out of favor? Last time I got the other stuff at Radio Shack. Cleaned first with q-tip and alcohol. Just a bead and let it spread itself. I still have the video I followed and saved for paste posters. I should ask you hardware experts for reviews.