Computer graphics issue--any ideas?

Factual Questions
1

A week or so ago, my computer screen started acting strange. It started showing weird flickering lines all across the bottom two-thirds of the screen. This was intermittent but was happening more often than not. I figured my graphics card was going (even though it was only about 6 months old and a high-end one). So I called the company that made it, and they agreed to send me a replacement.

The replacement arrived yesterday. I installed it this morning. Everything seemed to be working fine, except that it didn’t seem to have the nVidia driver/control panel anymore–I couldn’t change the resolution to 2560x1900 (native resolution–it’s a 30" monitor). So I re-downloaded the drivers and installed them. Now not only does the control panel not show up, but the artifacts are back! In a different spot this time–instead of the lower two thirds of the screen, they show up around text, and in random points around the screen (but always the same random points).

I called the company again, and the guy had me uninstall the driver, re-install an older version that he knew was working correctly–no luck. I couldn’t get any version of the driver to install correctly. Even so, though, the machine was working fine previously with the other driver, so I’m wondering if the driver is the problem at all.

I asked him what else might be causing it, and he said it might be a memory problem, a power supply problem (unlikely), or even a motherboard problem. It’s also unlikely that the second card is bad, though I guess it’s always possible.

I plan to try swapping out the memory for the older memory I replaced a few months ago (I went from 4gb in 1gb sticks to 8gb in 2 gb sticks) and trying the card in a different slot.

Does this problem sound familiar to anyone? Any suggestions of other things I might try? I’m not terribly hardware savvy (I can install memory and graphics cards, but couldn’t tinker with the motherboard, for instance). I’m very much afraid I’m going to have to take my computer in and have it worked on, but I’d rather avoid that if possible.

BTW, it’s a Windows 7 64 bit machine.

Thanks in advance!

2

Was it an 8800?

It’s insane how many of those I’ve heard about dying in the last month.

3

Nope, it’s GTX295.

4

What’s the power and heat situation like?

5

The power supply is overqualified (I can’t remember what it is, but I checked when I bought the card–I think it’s 1000 watts). Heat is fine. I’ve never had any problems with overheating.

6

Do you mean “Heat is fine because I just checked it” or “Heat is fine because I’ve never had problems with overheating (until now, maybe)”?

7

Well, okay, I didn’t actually check it. But I did have the machine open and it didn’t seem to be terribly hot in there. I don’t know how to actually measure it, though.

8

Google for and install SPEEDFAN.