So I've recently (about 3 months ago)built a new computer. Everything fit nicely into the case, and it started up wonderfully. After a couple days of smooth running, and not doing anything too intensive, it happened. The screen went to static as did the noise. This occurred twice more during the course of an hour, each time with no real reason. The events seemed random. I updated the internal gfx drivers, and voila, it stopped. The problems had gone away, and I eventually got my new graphics card, and still no issues. All seemed well.
That is, until about three days ago. I had been playing a game for a while, and it happened again, but this time with no graphical artifacts. It just froze, and the sound continued to buzz through my speakers. This happened twice more before I turned off the computer for the night. The following day, the computer had the same issue, but it also randomly restarted rather than freezing, and during the course of rebooting it restarted twice before finally getting back to the welcome screen. These events are as random as before. Now it freezes before getting to the desktop, and won't stay on for more than 10 minutes or so. This of course happened after being on and running for nearly six hours with no issues. I'm really unsure the cause of this. I hope it's not the Mobo, as it is likely past the date of being able to return for a refund. I've ordered a new PSU because I feel it could probably be upgraded anyhow. I'm goingto test the new PSU tomorrow, and hopefully that will fix it. My current PSU is approximately six to seven years old.
I dont think the first event was related to the second one, that was defiantly the graphics card like you said. The PSU could be the problem now and even if its not there's no loss really seeing as how old it was, but another thing to check is your ram maybe, but if you just built it then really it shouldn't be failing already.
What brand is the RAM?