Asus P5N-E SLI and Gigabyte GTS 450 issues

For the past 2 years or so, I've been running my Asus P5N-E SLI with two Nvidia GeForce 8600 GT video cards. These cards were running 4 monitors, so it was not in SLI mode.

I wanted to upgrade the video cards and power supply. I just bought 2 Gigabyte GTS 450 video cards. I also bought a new power supply (Rosewill 630 watt PS). I first just installed the power supply and everything worked fine.

When I installed the video cards (non SLI - just feeding 4 monitors) and booted the computer, it took a long time to get to the POST screen (about 2+ minutes). Then I loaded the drivers (for my Win 7 - 32bit) and everything worked great. After 10 minutes, 2 of my monitors just went blank and the computer locked up 2 monitors off the same video card). I rebooted and everything was fine again for about 5 minutes and then the problem repeated.

I then got the latest BIOS for my motherboard. Booted the computer and the exact same thing happened again. I should mention that everytime it took a very long time for the initial POST screen. After another boot, 2 of the screens didn't come on at all. Computer works fine, but only 2 screens show up. More reboots didn't solve this (and the POST is now taking 5 minutes!). I switched the 6 pin power source going to the cards to make sure it wasn't a bad power pin and still only 2 monitors come on (same 2 as before).

Next, I switched the two cards in their slots to see if it was a defective card. Again, only 2 monitors came on, so it's not the video card. I'm now thinking maybe one of the PCIE x16 slots is bad. So I removed both cards and replaced them with my old cards and everything works great!

The video cards are PCIE 2.x while my computer's slot is PCIE 1.x. I know they are backward compatible. But could this be causing the issue? Or could it be that my new 630 watt power supply isn't capable? I have no idea what else to do. Any advice is appreciated.
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More about asus gigabyte issues
  1. PSU, never ever buy that brand, they make crap sure some of their crap is better than some other crap but it is still crap. Return the crap psu and roll the dice on a more reputable brand like Antec that usually has a better chance of working.
  2. I suspect that your PSU is not quite up to the task of powering the 450s. Do you have access to another PSU to use for troubleshooting?
  3. Thanks for the responses. Unfortunately, I don't have another power supply to try. My old one was an Antec 500 watt and was making some high-pitched sounds, that's why I bought this one. And I had no idea this brand is crap. I got it for roughly about $50, so I'm not gonna go through the hassle of returning it by mail to Newegg. But I'll try to stop by Frys over the weekend and try a more powerful one.
  4. Understood. Good luck!
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