Computer boots up to black screen with white underscore in the top left.

[ben.batman05]

After starting up a game one day the computer would only show a black screen with a white underscore set up. After reseting it showed the same screen again. No way to access the BIOS, even when hitting the appropriate function buttons. Their is only one hdd in the system. When unplugging everything in the USB ports and the HDD, it still booted up to the black screen. After so many resets the PC finally booted up the normal way. It allowed me to enter the BIOS. I was able to to reinstall the windows. The computer was working for about 4 hours until it again became the black screen with white underscore. What problem do you think this could be? I just recently purchased the hard drive so I don't think thats it. I think it may have to do with the 9 year old power supply, but I'm not sure.

Also the specs in case it pertains to anything is a prebuilt from 2008 called the XPS 420. The only upgrade is the Graphics card is now a 6700.

 

[mark.potocnik555]

This might be a solution for you.
Your CPU and RAM should be replaced and also as you said the PSU. It appears that there was no power to boot up the system and then the PSU got back some strenght for those four hours. So yeah get a stronger CPU and some more RAM and if necesary new MOBO. This is just my solution to this problem. If you liked it make sure to mark it as the best. Here is also a post i found you can try to do to test a dead PSU.

 

[hemkanishka777]

That u mentioned u can't access the BIOS when booting. I think there's a problem with your basic components of the PC.
Try reassembling pc & check weather u can start windows normally. If it gives the same error u should check ur other parts(RAM, PSU, Cpu etc) try connecting those parts to another working pc..for that u might need to ask for friend's PC i guess!
Test 1 part at a time & notice what component gives u error.