Computer is clunky and slow after GPU replace

[Frozyn]

Hello, i'm having a dilemma in which my computer is running very inadequately after i replaced my GPU.

Here's what happened; i ordered a gtx 560 2 GB to replace my 1 GB HD Radeon 6950. I got it, uninstalled all drivers via control panel and shut it down, replaced it carefully by unplugging the 2 4pins from the PSU and detaching it from the MB (all the while having my static wristband in place). Attached the gtx 560 to it, started my computer up and downloaded the new drivers from the CD then from the website for the newest ones.

I started up WoW and found a substantial performance decrease, unsatisfied i deleted all drivers, took it out, put my Radeon gpu back inside and downloaded all drivers for it again.

NOW my computer runs so terribly slow that Minecraft performs at 1-10 fps when it generally would stay around 100 fps.. Websites are slow to scroll through and open, maximizing applications is slow, Steam is freezing, etc..

If you need any details, let me know and ill tell you, thanks. As to why this is happening... i have no clue and any help is much appreciated.

 

[Supernova1138]

Switching between graphics vendors can cause some problems with the drivers. Use a program called driversweeper to clean out the old drivers before you install the new ones. Failure to do so can lead to all sorts of performance problems.

Also, you actually downgraded your video card. The 6950 is about 10% faster than the 560 non Ti, the only advantage that 560 has over your old card is more video RAM. Most games won't benefit from the extra video RAM unless you are running at ultra high resolutions, and even then, the 560 will run out of steam before you run out of video RAM. The only games where this might not be true are Grand Theft Auto IV, Battlefield 3 on Ultra settings, maybe Crysis 2 with the high res texture pack, and maybe Max Payne 3.