Help. computer wont post

[bEngineering]

I recently built a new build with a sabertooth z77, intel i7 2700k, 8gb corsair ram, a sapphire 7970 and some HDD and ssd. It worked fine until one time in the motherboard menu I changed the settings to high performance, from default. I saved and rebooted and ever since then it hasn't POSTed, and my monitor doesn't turn on, just stays on standby. There's a red light indicating a problem with the graphics card but I don`t know what. It turns it self pf after about 15 secs and reboots and does it all over again. I tried taking the graphics card out and running on the in built in graphics card in the CPU but that won't work either. I've taken it to pieces a couple of times and put it back together but no change.

Anyone have any idea what's going on?

Is there a way to reset my motherboard and might this help?

 

[TheBigTroll]

you can use the clear cmos button the reset the bios and try that