BleepingComputer.com: Problem with display - Squares on screen

Hi, I was having a problem and was wondering if anybody could help me remedy this. I installed a new geforce 8400 gs video card on my dell dimension 5150 desktop with on-board graphics and after I switched to the new card, squares began to appear in the middle of my screen within minutes after restarting Windows XP. The boxes would flicker when watching a video or moving the mouse, and inside the squares were what appeared to be parts of a window that was open previously. When I scrolled up or down a Firefox browser, more squares would appear vertically.

The problem would go away after I reverted back to the on-board graphics.

Thinking my card was defective, I had it replaced with the same one and now I am having the same issue. Do you think it's the motherboard? I've inckuded some screenshots to show you what I'm dealing with. Any advice would be great, thanks.

I'm wondering if your power supply is not strong enough to hold the added video card.

Have a look at the power supply and see if it's marked 250W. If it is, I would definately recommend a more powerful power supply.

350 Watts should be good for what you have including the video card.

I'm also wondering if your 8400 had a power connector on it. If it did, make absolutely certain it is plugged in tightly.

Hope this helps,

Funny you should ask. My old 305w dell ps recently just failed me after 3 years so I replaced it with a 450w. Also, there isn't a power connector to this video card. hmm...

Can you give us the name and model number of the new power supply?

It's a Kingwin ABT-450MM power supply