We usually only think about thermal paste during new system builds. But you may not know that thermal paste dries out over time and needs to be replaced. So how often should you replace thermal paste? And why do you need to?
How long thermal paste lasts depends on how hard you use your computer. It’s best to replace it every 3-5 years or so, if you keep your system that long, but there are other times it’s a good idea to replace it too.
Why you need to replace thermal paste
The rules around thermal paste have changed. I can open up a Commodore 64 from the mid 1980s, and the thermal paste on its chips is marginal, but probably OK. But modern chips generate more heat than those chips of yore did. They get a lot more work done per watt dissipated, and they do a better job of cooling themselves. But when they’re running full throttle, they shift more heat.
Thermal paste’s job is to fill in those microscopic gaps between your CPU’s heat spreader and your heat sink. Even when metal seems perfectly smooth, there are small gaps between them, and those gaps act like an insulator. When you fill those gaps with something that’s a better conductor than air, you improve heat dissipation.
Australian tech journalist Dan Rutter tested various thermal compounds in 2002, and he included toothpaste and Vegemite in the test for comic value. The toothpaste actually worked better than the proper thermal paste, at first. Meanwhile, all the proper thermal compounds performed identically. The difference, though, is that the toothpaste will dry out in a week and perform worse. That’s why we don’t use toothpaste and save a few bucks.
The major difference between thermal compound that costs $5 and a competitor that costs $10 is how well it’s going to perform a year from now. The difference when they’re both new will be marginal at best.
How often to replace thermal paste
Changing it more frequently than the manufacturer recommends won’t hurt anything, but there’s no need to be obsessive about it. If you’re inside the machine anyway and have thermal paste on hand, then sure, there’s no harm in doing it. But I don’t have a calendar reminder, if that tells you anything. And I don’t think you should either.
Sometimes you can tell when the computer needs new thermal paste. If the fans speed up while they’re doing something that didn’t used to be demanding, that can be a sign it’s time to replace the thermal paste.
Many enthusiasts don’t keep their equipment 3-5 years. But that brings up another point. When you go to sell your used parts, you should consider replacing the thermal paste beforehand, then mention in your ad that you did. You’ll get fewer lowball offers and have a bit more leverage when negotiating the price. You’ll probably sell it more quickly too. You can use the leftover thermal paste from your new motherboard/CPU combo, since a tube of thermal paste usually has enough for around 4 applications.
If you’re comfortable opening a game console and performing this surgery on it, it helps those sell better too.
Why my friend replaced thermal paste on new equipment
I have a former coworker who routinely replaces the thermal paste on any new equipment he buys. If he gets a new laptop or game console, he takes it apart, takes off all the heat sinks, and puts Arctic Silver on the chips, then puts it all back together. He does the same on the GPUs he puts in desktop machines.
It allows him to eke just a bit more performance out of his equipment.
It seems silly, almost superstitious, until you think about it. The OEMs aren’t using expensive thermal compound. They’re using whatever they can get cheaply in huge quantities that will do the job. And it’s anyone’s guess how much they glommed onto it at the factory. It’s possible that premium enthusiast-grade thermal compound may slightly outperform lowest-bidder thermal paste right away. That’s even more likely if you apply the proper quantity, which should be between a grain of rice and a pea in size, then spread across the full area where the two surfaces some into contact. It’s an even better bet that it’ll outperform the cheap stuff when they’ve both been on the job for six months.
I’m sure at least one person will chastise me in the comments for saying Arctic Silver rather than some other brand. He’d get similar results with your favorite brand of $10 CPU compound too. Using a good brand and applying it properly is more important than which premium brand you use.
The end result is when his CPU and GPU turbo boost under load, they boost slightly longer, because they stay cooler. The difference isn’t a lot, but you’re paying attention, so you notice the system not straining under load.
So don’t forget this step when refurbishing a computer
It’s surprising how well an old computer performs when you install a fresh copy of Windows on it, especially when you put an SSD in it.
But if you want to improve its long term reliability and give it a touch more performance, do what my friend does on his new systems. Take off the heatsinks. Clean off the old thermal grease. I use naphtha or mineral spirits. Some people use rubbing alcohol. Use what you want, don’t flame me.
Then place a dab of new thermal compound on the chip after the solvent dries. I use pressure to spread the compound around, rather than trying to spread it with a razor blade or something else. You’re more likely to create air bubbles that way. Especially when the heat sink attaches with screws, you can do a good job spreading it just by screwing down the heat sink and alternating between screws in a bowtie pattern. I cinch each screw down about halfway, then crisscross around until all of them are tight.
Do vintage computers need new thermal compound?
Putting heat sinks and thermal grease on vintage computers is controversial. The combination heat sink/RF shield Commodore used isn’t a great heat sink. If you’re going to use it, then sure, put new thermal compound on. But if you’re going to use new heat sinks, the thermal tape the heat sinks come with is probably fine.
Any game consoles that came with heat sinks can definitely benefit from new thermal compound.
On vintage PCs, modern thermal compounds are probably a bit overkill, but it’s what we have and it won’t hurt.
Keeping vintage chips cooler helps them last longer, and we all want our vintage computers to last longer. So I’m certainly good with using better thermal compounds and better heatsinks inside of them, especially when I can do so without doing any permanent modifications.