download the gigabyte manual from
http://download.gigabyte.eu/FileList/Manual/mb_manual_ga-880gm-usb3_v.3.x_e.pdfgo through it thoroughly and set up according to your hardware , I think there will be set of IGX configuration options ,under intelegent tweaker settings .but it will be there somewhere ,just go through the options ,and you should find it .
I looked at the ebay link you gave and the PC there ,I am surprised they cut corners as they did ,a decent board and processor ,but cheepo mustang memory ,and a generic 450w PSU . I would heve preffered corsair memory ,and at least a 650w psu. I priced the parts up ,and the whole lot could have been bought (in stock) from 2 uk dealers ,for £60 less than their asking price . you should shop around if you want to biuld your own ,at least buy quality parts ,scrimping on a PSU etc , is not a good idea for future reliability. I have pointed out your graphics as a possible cause because you said you had a warning about crossfire settings and you should not have ,if the bios were set to use your card in the right way .but to be honest ,your BSOD problem could be caused by a number of configuration problems . its a process of elimination ,be methodical and keep a record of each setting you try .
PS clicking on the above link will simply open the manual ,if you want to download it , then , "right click ,and save target as"