GPU burnt. Soot on PCIe slot. Can I clean it or use another slot?

[Mookeylama]

pc started smoking and terrible smell. shut everything off. figured psu or mobo. but after inspecting, there was brown soot on the top of gpu, and attempting to boot gave the beep code for no video (according to American Megatrend bios beep codes).
i think it was bad house wiring, as we'd been having issues w/ some wiring in that area. so had an electrician fix some stuff (he did find issues there) and he installed a dedicated electrical line for the PC.

so removed gpu and that pci slot is pretty messy. one half caked w/ black crusty charred soot or ash. this is a pretty pricey pc. decent build back in 2012. and i'd like to save it for secondary use. now that gpu is removed, was gonna try to boot and see if i can get onboard video (3770k and z77 Sabertooth mobo). if it'll boot, i'd like to get a gtx1060 or maybe 1070, and just to be safe a new evga G2 psu (the TX850 Corsair seems fine, but to be on safe side).

so my questions...would it be ok to try cleaning the soot and crust off the top PCIe slot? if so, best way to clean? q-tips?

here's a pic of the Sabertooth z77
http://cdn.overclock.net/8/83/500x1000px-LL-83c8d9da_2013-01-13_041024.png

so clean off top light tan slot and install new card there...or put new card in 2nd (brown) slot? any advice welcome. thank you!

 

[geofelt]

Nothing lost in trying to clean off the mess.
I would use alcohol and a clean cloth.
Be careful with the contacts in the slots.
Perhaps wrap a thin knife with a alcohol soaked cloth to get into the slots. Be gentle.

And... Consider the possibility that the TX850 failed to protect you from damage.

 

[alceryes]

If you can get the first slot clean (hold it upside down and take a couple cans of air to it) use that. You need to clean it regardless. If you've got conductive material in that slot the MB probably won't post anyway.

 

[USAFRet]

And... Consider the possibility that the TX850 failed to protect you from damage.

This right here.
Bad house wiring should never have traveled past the PSU.

 

[Mookeylama]

If you can get the first slot clean (hold it upside down and take a couple cans of air to it) use that. You need to clean it regardless. If you've got conductive material in that slot the MB probably won't post anyway.

ah, that may explain why even w/ the gpu out i still can't boot. i'm still getting the same beeps (1 long, 2 short. ASUS states that beep code is for bad ram but American megatrends states that code is the bios for bad gpu vram. i checked my ram and it seems fine).
i cleaned the cleaned the pcie slot but there's about an inch of melted crust in there that won't come out. looks like some tiny copper wires pulled out too when i removed the gpu. so maybe there's still conductive material in that slot. shouldn't the mobo auto find the onboard graphics if the gpu is unplugged and not working tho?