IF a screw fell in the wrong way, it could have caused a short circuit between two wires or pins of a chip... which could have damaged a component.
If you're lucky, the result was just a broken fuse and replacing that fuse would fix the power supply... however, since you got sparks, there's a significant possibility a component inside the power supply got damaged.
It's unlikely you damaged anything else in your computer, power supplies usually have protections and are designed to turn themselves off and not send bad power to computer parts.
My advice would be to just buy another power supply, since you don't have the knowledge to test the power supply and attempt to repair it. You could go to some service place but most likely it won't be worth it - it would cost you 20-50$ just for some person to open it up and do some basic checks, so you'd probably be better off just buying a power supply.
If you want to risk trying to repair it yourself, i'd advise by starting with checking the fuse for continuity with a multimeter, then checking the mosfets on the primary side and see if they're shorted or not.
All modern cards will shut themselves down before any real damage occurs. As for the dust- 1070s are still quite new, so shouldn't have too much dust. You can blow it out with a your mouth, a compressor or a can of compressed air. Just try to not spin the fans.
Don't worry about the card too much if it works. GPUs normally last ages and modern ones have a lot of protective measures for them
Proprietary reacted to mariushm in PSU sparked
