Graphics Card problem - Pixel issue

[anty1]

I recently purchased a Nvidia 9800 gt, soon after I installed it I started to realised wierd pixels apearing in the top left hand corner of the screen and they only appear there. It usually happens when I'm looking at interactive content such as videos and pictures.

I have also discovered that the problem seems to affect old games such as Diablo 2 and Warcraft 3 after a short play time they game will freeze briefly and screen tearing will appear making it unplayable. But as far as newer games go (WoW, Empire: Total war, TF2) they seem to be uneffected in any way.

Is the graphics card just faulty or is it something else. My monitor is a pretty old Dell flatscreen but I'm sure it's the graphics card. I have the latest drivers plus I've reinstalled them to try fix the problem. The graphics card manufactor is Zotac.

If there's any other info you would like to know please ask.

Here are some pictures of the pixels appearing.

 

[Gulli]

It's probably software (may get fixed by newer drivers, may be caused by newer drivers, since no one pays attention anymore to what newer driver do with old games), it's definitely not the monitor and probably not the card either.
I've seen some weird things: on my PC games like Supcom FA, Sims 3, CoD4 and Crysis Warhead run flawlessly while the animated menu's in the old game C&C Generals don't work.
On my girlfriend's (less powerful) PC the old game rollercoaster tycoon 3 has a lot of tearing but the Sims 3 and CoD4 don't.