Dell XPS became slow as hell overnight

Question

I have a Dell XPS 9650 with a i7-7700HQ with 16GB of RAM and a 500GB SSD. I bought it a year ago (around September 2017) and it has been a good laptop, both fast and reliable.

However, around a week ago I realized my XPS had gotten slower over night - my first hint of this was that league of legends, which I used to run between 80-140FPS, began to drop to between 15-50 FPS out of nowhere. I also realized that every program on my computer began to start slower, and even pressing the arrow key on the Boot Menu (where I choose between my Linux Boot Partition and my Windows 10 one) lags very significantly.

I suspect it's the processor or ram since the problem exists even in the boot menu, but I'm not sure why hardware would degrade almost over night. There was also a system bios update around that time, but I tried reverting it and really nothing has changed.

As far as tests I've done, I used the Memory Diagnostic Test (although I'm having trouble viewing results - I may have to retest). I've also done stress tests for an hour or so and not discovered any issues with temperature or instability on my system, so I'm really confused. Does anyone have any ideas or possible solutions as to what happened to my computer?

Answer 1

I've experienced a similar problem before with a XPS9560. It turned out it has been throttling to lowest CPU clock frequency (800 MHz). Like you, changing the firmware version made no difference. (It was running Linux as well.)

On Linux you can check the CPU frequency with cat /proc/cpuinfo or by using sudo powertop.

What finally fixed the problem was to disconnect the battery and discharge the laptop after that (hold the power button for a few seconds). For this you need a screwdriver to open the bottom, but it should be quite straightforward as you don't have to remove other components.