Video Card stays in idle mode

Hi all. So recently as I have been investigating why my computer seems to be acting sluggish to load scenery and textures I have noticed that my video card no longer stays in hi power 3D mode. It goes from idle speeds and power to high power when I first launch the sim, but then after a minute or two it goes back to low power idle mode and speeds. The difference it makes in the sim is crazy! The card is a BFG Nvidia GeForce 7800 GS that runs at 275 MHz in idle and 400 MHz in hi power mode with the memory running 1200 MHz and 1250Mhz respectively. I have the latest newest driver for the card and even reinstalled it but it did nothing to help. It is an old card and old mobo but it has been running the sim great until recently and I cant figure out what has happened. I havn't made any changes to any software affecting it and the Nvidia software does recognize FS9 as a 3D app. The temperatures are fine, it barely reaches 110 F even when in high power mode, and my power supply has no issues with the 12v rail. I am running Win XP SP3 on a Gigabyte 8IPE1000GA Pro 2 MOBO, Pentium 4 @ 3.4 GHz, 4 Gb of RAM, BFG Nvidia 7800 GS video card, Soundblaster X-Fi sound card and 500 Gb HDD thats just under half full and it is 32bit so only 3.4 Gb of RAM is recognized. Any help is appreciated. Thanks and happy flying