Cannot figure out why my PC is lagging

Turned PC on today and it’s lagging on the desktop on startup low cpu/mem usage can’t tell from task manager. Maybe desktop window manager it’s like 3%. It can’t find the most recent windows update. Have Malwarebytes premium. Tried scanning everything no errors. unplugging USB everything is normal.

8700k at 4.7
ASUS rtx 3090 tuf oc at stock
32gb DDR4 hyperx at 3200 mhz
ASUS z370 f gaming
Bunch of ssd’s
Seasonic focus 750w

It’s driving me nuts don’t know what else to do. Very bizarre. I did plug in a new 3.5mm aux cable for my speakers before I turned it on. I unplugged it no change. Not sure what to do. Never had any issues before. It’ll go away for a few minutes then come back.

Today I reinstalled windows core files with an in place upgrade and I’m running MemTest 86 overnight but the weird lagging on the desktop continues. How do I test ssds for failure as well as the gpu or even the psu it’s not really games that are an issue this pc is like 40 hours game stable and well as stress testing. I’m about ready to just build a new pc all I’d need is a cpu mobo psu case power supply and ram but I want to exhaust my options first. I don’t have any crashing or bsods or errors.

Try a clean boot.