Random black screens when playing game or attempting to watch videos

It only started back in ...July of this year, and began annoying me in the first part of August. I thought it was World of Warcraft, that was when it happened. Just bounding along, when my screen went black, and I had no control of my mouse or keyboard. I would have to physically turn off my power supply (power button was unresponsive) I chatted with blizz tech support on the phone after I had done their other suggestions, and I uploaded my dxdiag and a few other files to them. They stated they could find nothing wrong, but did see a few things driver wise that needed updating. I updated those, and played on.

It continued to happen, and I started to suspect my video card was going bad (XFX Radeon HD 6790) I contacted XFX and went through troubleshooting with them, and finally they RMA'd the card. I got a new card, GTX 560 TI (nvidia) and started from scratch. Uninstalled countless things I hadn't used in forever, used CCleaner to make my registry tidy again, and watched the black screens get worse and worse. I wrote back to XFX and let them know their card was fine it's something in my system) It began happening with going to youtube, or watching hulu, it happens now (I am praying I can get this typed out before it goes blank) so randomly. I finally, after hours of searching found this forum. I downloaded that file capture thingy, and have several zpped. See, it doesn't always leave a dump file when it does it, and that is most frustrating.

I can't play my game at all now (WoW) when it loads, pop goes the black screen, and likely as not, I won't get a dump file. I can't figure out what's happening, and I need your help. Can you please translate what's happening here and give me a clue where to go?

Oh, I forgot one thing. I can't seem to run any kind of video stress testing. Furmark, for example, the moment I start it...black screens.

Thanks!

It might have gotten moved because your machine isn't blue-screening.

Try running memtest even though it might crash. You might see a RAM error before it does.

I can think of a few things that this might be:

1. Faulty or failing power supply
2. Overheated processor (Use Speedfan or Coretemp to get your processor's temps)
3. Faulty RAM

I seriously doubt that it's your graphics card.

Try memtest and get us your CPU temps (please), and we'll see what we can do.

So your browser is Google ... let's just run a quick scan with DDS (doesn't do squat), but it shows me what might/could be wrong.

Download DDS from one of these links:
DDS.com
DDS.pif

• Disable any script blocking protection
• Double click the dds icon to run the tool.
• When done, DDS will open two (2) logs:
  1. DDS.txt
  2. Attach.txt <--- will be minimized in the task tray
• Save both reports to your desktop.

Include the contents of both logs in your next post.
The scan will instruct you to post Attach.txt as an attachment.

Try going down to one stick of RAM and seeing if that makes it work. If it does, swap out that stick for another and see if it works again. Then try the third stick...

It's possible that the memtest didn't pick up a second problem in another stick. Try one stick at a time and see how that works.