Yikes! Silly question, but have you cleaned the inside of the laptop?
A quick guide for anyone who thinks they may need to do this:
-
Unplug the power cable and take out the battery.
-
Unscrew all the access panels on the underside, turn the laptop back right way up, open the screen/lid to 90ยฐ and stand it on its side. This is to create as many "holes" in the laptop chassis as possible so dust can be blown out effectively, even back out through the keyboard.
-
Using compressed air, blow a few extremely short bursts of air backwards through all the exhaust vents. This dislodges all the grunge which has accumulated on the leading edges of grilles, heatsinks and obstructions due to the constant one-directional air flow. Then do a couple of short bursts from the opposite direction (i.e. into the fan air intake) to ensure the dust you just blew backwards hasn't simply lodged somewhere else instead. Repeat this back-and-forth process a few times until you can't see any more dust coming out of either "end".
COMMON SENSE WARNING: Of course, if you're using an air compressor be very careful to limit the pressure and hold the nozzle back a few inches/cms from the actual vents as you can easily dislodge or damage components otherwise.
- If you can get access to the fan, CPU and GPU heatsinks, a large soft watercolour paint brush is great for getting in the nooks and crannies to get them shiny again (not unlike archeology!). A couple of gentle blasts of compressed air after brushing and they'll be like new.
I do this at least 3 or 4 times a year and (even though I only use it at home) a cloud of extremely fine dust is inevitably emitted from my laptop's innards every time.
A well-insulated CPU (i.e. covered in a nice fur coat of lovely fluffy dust) and blocked pipes will overheat in seconds and blowing more air through it (with an extra fan for example) could just cause more dust to accumulate, exacerbating the problem. All the more so in a smokey atmosphere which, Csaba, considering your laptop's current AND previous owners, could explain a lot! ![:wink: ๐](https://community.sketchucation.com/assets/plugins/nodebb-plugin-emoji/emoji/android/1f609.png?v=fe137e50c39)
Re: the incredibly slow start-up, it really sounds like you need to do a full OS resintall.