Screen width shinkage at start

After Geforce 6200 (256Mb) AGP card warms up, it expands to normal screen width. Returned PNY GeForce 6200 for refund and then purchased ATI card Diamond Stealth Radeon 9550 (I don't care if it's slower GPU). At least my ATI card does not require a warming up period for the correct start up screen resolution size. I lost faith in Nvidia cards a long time ago and Nvidia still hasn't corrected this problem after five years. I used an ATI Radeon 9000 Pro card for five years and it still works great, but the 9550 is in my PC now. I don't care if Nvidia cards have a much better image quality. I prefer correct start up screen size over above average quality.