Apparently, this issue is NOT new and is posted at the EVGA web-site. EVGA has released at least 2 BIOS updates specifically for the 7800GT in an attempt to correct the problem which includes reducing the geometry delta in the BIOS by 40 MHz (which does not appear to actually reduce the clock speeds?).
Perhaps this new driver release from nVidia will correct the issue. I hope it does because I have very little interest in flashing the BIOS of my 7800GT especially if it reduces the performance of my card. That's just plain wrong (i.e., I bought the card for the "advertised" performance and NOT with the intent of slowing the performance just to get "normal" visuals).
Looks to me like nVidia shipped a fair amount of "marginal" quality chips for the 7800GT. That'll teach me to buy a recently released product.
Anyone else have this issue with a NON EVGA 7800GT?