Unknown video/boot up problems

Hello, I have been having problems with my computer lately and im really not sure what the problem is. It is a brand new computer that I have sent back to get fixed, it worked fine for about 3 weeks and now its messing up again. I ordered from cyberpowerinc.com.

First of all, when I try to a cold boot up, like the first time for the day, the computer sometimes the monitor does not come on when I try to start it, I have to unplug it from the wall and then it usually starts up after that. Also a couple times when it has started the DOS letters that list like the system info before it goes into windows are all scrambled and when it gets to the part where windows starts it just freezes.

Another problem is that sometimes when im playing World of Warcraft the screen just freezes, sometimes it kicks back in like 30 seconds later, but other times the monitor just shuts off as if I unplugged the monitor and I have to unplug the computer. The computer is less than 3 months old and I know that the specs are way more than enough to run the games im running. Friends of mine have told me that they think the power supply is not enough for the computer, others have told me they think I might have a faulty video card. Two different people from tech support from cyberpower told me the power supply is more than enough, so I am not sure.

The thing that really gets me is that sometimes it just works fine and I have no problems at all, like right now I am on it and there is no problems. Any help before I demand my money back from the company would be greatly appreciated.

Specs are below, the hard drives are striped and the video cards running on SLI mode.

CASE: ASUS Vento 3600 Mid-Tower 420W Case
CPU: (Socket AM2) AMD Athlon™64 X2 4200+ Dual-Core CPU w/ HyperTransport Technology
CD: (Special Price) 16X DVD±R/±RW + CD-R/RW DRIVE DUAL LAYER
CD2: 16X DVD ROM
FAN: CoolerMaster Liquid CPU Cooling Fan System Kit + 2 EXTRA CASE FANS
HDD: Gaming Hard Drive (10,000RPM SATA150) (SATA150 - Western Digital Raptor 74GB 10,000RPM 8MB Cache WD740GD )
HDD2: Gaming Hard Drive (10,000RPM SATA150) (SATA150 - Western Digital Raptor 74GB 10,000RPM 8MB Cache WD740GD )
MOTHERBOARD: (Socket AM2)GigaByte GA-M55SLI-S4 nForce4 SLI Chipset DDR2/800 SATA 16x PCI-Express MBoard w/GbLAN,IEEE1394,USB2.0,&7.1Audio
MEMORY: (Req.DDR2 MainBoard)2GB (2x1GB) PC6400 DDR2/800 Dual Channel Memory (Corsair XMS2 Xtreme Memory w/ Heat Spreader)
POWERSUPPLY: **Recommended** NZXT PF-500 500Watt Power Supply
RAID: RAID 0 Striped Disk Array for Faster Performance - Requires 2 Identical Hard Drives
VIDEO: NVIDIA Geforce 7900 GT 512MB 16X PCI Express Video Card
VIDEO2: NVIDIA Geforce 7900 GT 512MB 16X PCI Express Video Card

Thanks.

 

You got a nice power supply on that thing. Also it is not a video card problem. This may sound stupid, but I suggest you get a refund while you still can. I've heard of people having problems with cyberpower before. But that is definently something serious.