Your problem is almost certainly one of the following:
You may have an obsolete ROM BiOS. You should go to the motherboard manufacturer's website (which is definitely NOT an Asus P9x79 LE as you indicated -- that's a socket 2011 motherboard that accepts only newer Intel Core i and Xeon CPUs) and obtain the new BiOS and instructions on how to reflash your BiOS. Some are as easy as a software upgrade; others are a lot more complicated. You should do this periodically in any event, but it is now highly advisable given the problem you describe.
You also need to update your drivers. There are lots and lots of these. I would start with the video card driver, but there are many others you are likely to need to update. There is a fairly large variety of software, some better than others and a few that are freeware, that can help you with this. Drivermax (available at http://www.innovative-sol.com/dmx.htm) is allegedly one of the better of these. Most of them cost around $30.
If this doesn't solve your problem, it could be a CPU cooling issue, but that would normally set off an audible alarm in your system assuming the builder correctly installed the little speaker. It might also be corrupt system files, which you can discover (and correct if your O/S was installed correctly) by running the command prompt as administrator and executing the command (no quotes) "sfc /scannow".
Good luck. These darn computer thingies can be right tricky!