The importance of regular cleaning

ubuysa

The BSOD Doctor
I'm living in a particularly dusty environment at the moment; they're renovating the large hotel opposite us. Consequently I've been cleaning my PC more often than usual - and usual is at least once a year.

I'd not done it for a few months now and yesterday I noticed that the colour of my keyboard light was much more yellow than the cyan colour that I'm used to - I have iCUE change the colour of my keyboard lights based on the CPU package temp, the yellow colour comes in at 50°C in my iCue settings. I immediately fired up HWMonitor to check the temps. At idle the package temp (AFAIK that's the only actual real thermometer in the CPU) was 57°C and that's way warmer than usual, and much warmer than I care to see it. It was clearly time for a good clean.

The outside of the front fan cover and filter was pretty coated with dust, but visually it looked as though decent airflow was still possible. When I took the front cover and filter off and held it up to the light it was clear that the dust was only cosmetic, air was able to flow through through there ok.

None of the blades on any of the fans looked particularly dusty. The leading edges of the front fan and the leading edges of the Noctua cooler fan had a thin layer of dust on them, but the blades themselves were pretty clean. The exhaust fan and PSU fan looked pretty clean all over.

There wasn't a particularly big build up of dust anywhere inside, visually the PC looked pretty clean, except for the excess of dust on the front fan cover.

But for the 57°C package temp reading I might have been tempted to give it a quick dusting inside with the air blower and leave it at that. Instead I decided to do a proper job...

All of the filters were removed, blown with the blower (not much dust in any of them really) and then rinsed in water and dried.

The front fan was removed and the blades and the area around the fan properly cleaned (I use cleaning wipes to do that). Again, not a huge amount of dust was removed. I did the same for the exhaust fan, even less dust was seen on here.

I removed the fan from the Noctua air cooler and cleaned the blades on that. Again, not a great deal of dust build up on the blades, but some on the leading edges. Then I directed the air blower into the Nocutua cooler fins. I did see a cloud of dust emerge as soon as the blower reached the cooler. Not a massive cloud but big enough to be noticeable. That's a big cooler and I don't believe that the small cloud of dust was actually blocking the cooler, it's certain that air was still moving through.

I blew what little dust there was from everywhere else of course, but the insides were already pretty clean. I'd seen so little dust overall that I was starting to think that the 57°C temp was most likely ageing paste - the PC is 6 years old.

When I put it back together and rebooted, the package temp was down to a cool 31°C and even under moderate load it's not exceeded 40°C yet. That is a massive 26°C temperature reduction just by cleaning a little dust.

I suspect that the dust inside the Noctua cooler was having a two-fold effect; in the first place it was likely acting as an insulator on the fins to reduce the ability of the heat in the cooler to escape easily and quickly. More importantly though, I think the dust in the cooler (and on the fan blade leading edges) disrupted the laminar airflow that good cooling needs. The chaotic turbulent airflow inside the cooler, generated by the layer of dust, massively reduced the ability of the air to capture the heat from the cooler fins. It's kind of like the effect that icing has on an aircraft's wings.

The lesson here, and the reason I'm posting this, is that just because the inside of your PC looks clean that doesn't mean that all is well. A laminar airflow through the PC, and especially through an air cooler, really is critical to cooling - and even a small layer of dust can disrupt the airflow enough to raise CPU temps by a marked amount - 26°C in my case.

Now that you've read this, take your PC apart and give it a really good clean. It will thank you for it. :)
 
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