hey guys i rebuilt my system about this time last year and have had really no trouble out of it till now. last week i had a friend who bought a GTX 770 and it was causing his system not to boot and crash in benchmarks and he asked me if i would but it in my system and test it because i had newer hardware. so we did and everything went well i removed my 2 radeon 6850s and uninstalled my AMD drivers and installed his GTX 770 and the nvidia drivers and ran some benchmarks and everything ran great. so we took out his card and uninstalled the nvidia drivers. when i put my 6850s back in my system i could turn my system on and it would POST and boot up into windows but when it would go to the log in screen my displays would go black and just flash. so i was thinking it was were i haddnt installed my drivers back so i unhooked 2 of my 3 monitors and tried to boot again and it did the same thing it would just go black and flash. so i just formatted my computer and everything was working and when the format was finishing it locked up and wouldnt finish installing my OS. then i started clearing my CMOS and that didant help. then i tied going back into my BIOS and setting everything back to default and ever since i did that and restarted my system will turn on but not give me a display. ive tryed to use the USB flashback on my motherboard because i was looking at my post code read out and i was getting a 72 post code and i looked around on the internet and it said do flash my bios so i tried to do that but ive had no luck getting it to work. ive also tried a brand new stick of ram i went to best buy and bought a new stick and that didant even let it turn on.
my system specs are
motherboard- ASUS Maximus V Formula
CPU- intel core i7 3770k
GPU- XFX radeon HD 6850 black edition x2
RAM- Gskill sniper 8gb in 2 4gb sticks
SSD- intel 112gb 520 series
HDD- 1 hitachi 500gb 2 WD raptor 75gb drives
PSU- corsair tx650
thanks in advanced to anyone who tries to help its really appreciated