Video Card Problems

I just finished building a computer cheap but not to cheap. My video card is going crazy after a few months and I don't know why. I don't know what the idle speed for the fan is but when I play a game my fan goes up to 6000+ rpm then the video goes out. I don't think it's the card because I switched cards with a old cheap one same problem but the video stays on. I got the card at microcenter openbox around five months ago I opened it and there are no thermal pads and barely any paste. Would this be a PCI-E problem? My card worked fine a few days ago. It's been getting hotter daily probably because there was no thermal pads on it the whole time.



Windows 7 Ultimate 64Bit
Motherboard Biostar H61MLB MicroATX
8 GB RAM Kingston HyperX
Intel i5 2400 3.1 GHz
Corsair GS700 PSU
Antec Kulher 620 CPU Cooler
Galaxy GeForce GTS 450 1GB (This video card is the one I use)
MSI AMD Radeon HD 4650 1GB (A card I use for times like this)

I have the latest Drivers So Far.