Testing a PC build

I built a PC awhile ago and was wondering if anyone could confirm that all the parts are working right. Lately I've noticed more noise comming from the tower (sounds like a coffee maker) and occasionally it shuts-down during boot-up. I also get odd graphical glitches in games and movies. Not to mention that the startup time has greatly increased from about a minute to maybe three.

CPU : i3 - 2100 CPU @ 3.10GHZ (is listed 4 times in the Device manager)
GPU : NVIDIA GeForce GTX 660

Actually, I'll just post an image of what the Device manager says (I'm not sure what I'm looking for   )



Lastly, what programs do you recommend for testing out your PC. As in, getting the benchmarks and all that.
Is there anything you could suggest that would better optimize my PC, I litterally just put the parts together and installed windows 7. No tampering with the settings or options.