Question Laptop has massive lag (very slow) ?

[InsanityCrescendo]

Hello everyone, so I'm at my wit's end. I usually can fix computer staff pretty easily but this is very weird.
It all started when my laptop (EDIT: Acer Aspire 5 A515-51G-58E ) suddenly started lagging a lot, to the point where the cursor was moving in steps. After a minute or so the laptop just turned off. I noticed that, while it was hooked to its charging cable, it didn't show as charging (the led that was supposed to be orange wasn't on at all).
From that moment I couldn't open it up again. I tried many things like unhooking the battery, the cmos and eventually I just removed the whole motherboard to see if I could check for any burns but I couldn't see anything. In the end, I managed to get the laptop to open* but now it's very very slow, almost like it was like the first time it did it before it turned off on its own.

• I checked the CPU with Prime95 and passed all the tests (EDIT: See below for more on CPU).
• I checked the memory with memtest and it passed (EDIT: 4GB integrated + 4GB stick).
• I checked the ssd (M2) and no errors.
• I did a fresh windows installI and same.
• I tried running ubuntu from a liveusb and it was still very slow.
• The weird(er) thing is that when the laptop is idle (fresh windows install) windows task manager shows a very low usage percentage, as it should, but speedfan shows a fluctuating usage from 20-%-35% up to 60% cpu usage (not equal between cores). EDIT: A youtube vieo shoots speefan CPU utiilization to 80%-100% and task manager's to <20%

I am out of ideas, besides the motherboard having some sort of fault that I can't detect (don't have the knowledge for such an examination).
Anyone knows what I can do? Unfortunately, I can't go to a technician right now.

*When I say I managed, I still don't know what did the trick. What I suspect to be the culript was static charge and the battery being at fault somehow. But anyway, after unhooking and hoking back staff I managed to consistently get it to open up (albeit without the battery and with the blue LED that turns on whenever you turn on the laptp not always working)

 

[Lutfij]

By fresh install of the OS and I'm assuming you're on Windows 10, did you recreate your bootable USB installer prior to reinstalling the OS? As for your laptop, did you see if the laptop had/has any BIOS versions pending update? Chances are that you might be having a corrupt stick or two of ram. Might want to see if you can source donor sticks of ram for your laptop.

With all things said and done, you forgot to mention the make and model of your laptop.

 

[InsanityCrescendo]

By fresh install of the OS and I'm assuming you're on Windows 10, did you recreate your bootable USB installer prior to reinstalling the OS? As for your laptop, did you see if the laptop had/has any BIOS versions pending update? Chances are that you might be having a corrupt stick or two of ram. Might want to see if you can source donor sticks of ram for your laptop.

With all things said and done, you forgot to mention the make and model of your laptop.

• Windows install: I made a new bootable usb with a windows 10 .img and did a clean install.
• BIOS is on its latest vesrion. But regardless, I would understand that doing a BIOS might mess with the machine, but even if there was a BIOS update that I haven't done, it shouldn't change anything with the laptop (but anyway, no BIOS update available)
• Laptop: Acer Aspire 5 A515-51G-58E
• RAM: The laptop has 4 GB integrated and 4GB stick so I can only check the stick. Leaving the laptop with 4GB or 8GB doesn' t affect its behaviour so who knows. Again though, memtest showed no errors.

I think the weirdest thing is the discrepancy between task manager's and speedfan's CPU utilization. There is a big difference and I must say the behaviour of the laptop is that of a machince out of CPU. But even though speedfan shows 100% utilization if I play a youtube video the temperature is fine at about 30-40C.
Also, the RAM area gets quite hot even at idle (or with a youtube video) but RAM is close to CPU so I don't know if that's affecting it.

Another weird thing is that copying something to a usb seems to make it exceptionally hot (more hot than it would get if I do the copy in another machine)