"Best" thermal paste ?

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"Best" thermal paste ?

Postby PDM » Sat Aug 30, 2014 10:08 am

Is there a "best" (and I realize this is subject to opinion) thermal paste?

Where I work, we have a number of Dell Optiplex 740s (minitowers) with Athlon 64 4600+ processors. They were purchased in 2007. Over the past year or so, several have exhibited the symptom of just locking up unexpectedly. Users can power them down with the power button and they will work for a while and then some time later...BAM....same thing happens.
I take them to the bench, run the Dell diagnostics (which find nothing wrong) and i take the box back to the user only to have the inevitable happen again.

Finally it dawned on me that maybe the processor is overheating, so I opened one up and removed the heatsink and the "paste" was hard as a rock. I cleaned it up and applied some Arctic MX-2 (which is why I'm asking this question), put it back together and when I powered it up the first time, the LED on the power button (which should be green) was amber (which for Dell is an indication of something amiss).
I took the heat sink off, made sure the paste was spread evenly, put it back on and it was fine. This same scenario has happened on 2 separate machines. I have had to remove and replace the heat sink a second time. Just wondering about that.

Which is a long preamble to this question.

Is MX-2 (or its cousin MX-4) as good as Arctic Silver? Or is there a better product?
I bought the MX-2 because it was the first one listed on the page on Newegg.
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Re: "Best" thermal paste ?

Postby Karlsweldt » Sat Aug 30, 2014 3:54 pm

Arctic Silver is one of the best. I use a #340 military-grade thermal paste.
There are many excellent types of thermal paste. But when applied, they should have the consistency of "sour cream". Not runny, not too dense. Only a slight amount is needed, spread evenly over the CPU heat spreader. Too much or too little, the CPU can overheat.
It is important to clean off any old paste before applying new. Denatured alcohol is preferred, but liquid lighter fuel (Naptha) does a quicker job.
Give the heat sink a bit of twisting to ensure the paste spreads evenly, before a final tightening down. If there is great resistance to lightly twisting the heat sink, it is properly secured. But if easily moved, then likely the original thermal transfer media was a pad. That must be used instead of thermal paste. Thermal pads can be up to 2x thicker when properly compressed.
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Re: "Best" thermal paste ?

Postby Mr T » Sun Aug 31, 2014 12:37 am

If you don't airdust and clean out the tower this is what you get, also those motherboards and power supplies suffered bad capacitors (bulging or leaking brown goo). It is worth cleaning the old paste off the CPU and heatsink base as karl noted with isopropanol and reapplying new. Thermal compounds are much of a muchness - the silver ones (Arctic Silver being the best known) are good on the overclocking front, but for average daily use are much the same as others including silicon based ones. CPU manufacturers will supply their own (in the retail box kits) which do the job. On laptops and video cards they use a hard patch or/and copper shim which again does the job - the hard patch is basically maintanence free. I clean my PC about every 6 months and have never had to replace the thermal compound unlees the CPU is upgraded which is about once in a blue moon!
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Re: "Best" thermal paste ?

Postby PDM » Sun Aug 31, 2014 2:39 am

Thanks to you both.

Yes, we have noticed several of this particular model with bad, leaking capacitors, but they still seem to run and whenever I disassemble a PC, I always blow the dust out of the heatsink and clean the old paste from the heatsink and processor.

Typically, if we would get a replacement motherboard or processor from Dell on a warranty deal, they supply a little syringe with just the right amount of material and I would put it in the middle and all would be well.
This is the first time we've used aftermarket thermal paste, and I've seen Youtube videos where people use the 'rice grain' or the 'pea' to describe the amount used, and just put the heat sink on and it spreads out and I've also seen videos where people manually spread the material out over the entire surface of the processor with their finger, so it's hard to know which is correct.

I guess the main thing is to use the correct amount and get it spread out as evenly as possible.
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Re: "Best" thermal paste ?

Postby Karlsweldt » Sun Aug 31, 2014 5:35 am

No matter how finely machined or polished two mating surfaces are, there still will be microscopic pits and bumps that prevent 100% positive contact. Only a very thin film of thermal paste is needed to ensure optimal heat transfer between the surfaces.
As to capacitors, there was (still is!) a plague on almost the entire electronics industry where they fail prematurely.. mainly due to a faulted formula that was pirated. Some were relabeled with different values than original by shysters. When a capacitor starts to bulge or leak, it is the final stages of failure. But still they can be bad, as internal shorting can pass unwanted voltages between circuits. Or fail to balance out AC signals to a pure DC level. The tops of all capacitors should be flat or slightly concave. There is a thread about "bad, bad capacitors" in the Tech Support folder. The offending brands are noted there. Bad capacitors can be replaced without too much difficulty, but the exact original values must be used. And should be rated at 105°C. More info at www.badcaps.net/
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