My brother has got a leadtek Geforce FX-5900 and had nothink but problems with drivers and conflics in games. 1st it seems that some drivers are not giveing 3dmark results without loosing visual performance then the games seem to work well with DX8 games well but DX9 games realy bad? The default clock speed should be 400 hes was 300 and on 3dmark 2001 he is only getting like 10500 plus points more than my GF 4 ti 4200. The only drivers that seem to work reasonable is the 44:03 drivers. Iv read that the ATI cards are 2 times as fast on DX9 games. Our systems are both the same other than Im using a Barton and he is using a Thoughgbred is my 512k cache real doing that well. Im getting max in 3D MARK2001 13500 he is getting 15006 being as our cards are so different in price whats up? I installed Halo in his system it ran realy bad because Direct X9b or the game has diabled Texture exceleration which could not be turned back on, my system ran this game realy well.

Could be driver conflicts. Try uninstalling all video drivers. Also use 'Detonator Destroyer' to clear out any remaining files and then re-install them again. Plus, go into the BIOS and reset to defaults in case there are any old setting still held. Also consider flashing the BIOS if there is an update available.

HI couldnt find a deternator detroyer for Win XP and have tryed loads of drivers and no unlucky that there is also no bios update.

Uninstall the driver for the 5900. Uninstall the card out of the hardware manager. Reboot. Reinstall the driver. This should fix your problem.