Keyboard/mouse/monitor won't turn on!

Hello
You should try just with 1 RAM, no connected drives, no additional video card, just the processor and see if at least the boot screen (or the BIOS screen) appears !!

So: Unplug, reset the BIOS (battery or jumper), the screen on the integrated card, 1 single RAM, the processor + cooler, no accessories, no drives, just a USB keyboard...

In short, do several tests with 1 different RAM.

Otherwise, take everything to a professional near you, but that comes at a cost !!
See you later
--
If the answer helped you: a little thank you is nice. If it's resolved: the green button at the top is better ;-)

Let he who has never opened a user manual throw the first mouse.

Did it work again?

So put it as resolved.

Hello
You say your PC turns on, but not the screen or keyboard/mouse...
If nothing shows up when powering on, it means the PC is not turning on!!
Otherwise, you should at least see the BIOS loading screen...
Just because the fan is running doesn't mean the PC is starting. It's just powered on!!
Check the processor and the RAM... And try without the graphics card, just the integrated one
Catch you later
If this response helped you: a little thank you is nice. If it's resolved: the green button at the top is better ;-)

Let him who has never opened a user manual throw me the first mouse.

The screen isn't off by chance.