While we've yet to run the BFG 7800 GS OC on our AGP reference platform, we have had the chance to run it on a decent AGP system:

Mainboard: Gigabyte GA-K8NNXP-940
Processor: AMD Athlon FX-53, Socket 940, 12 x 200
Memory: 2GB DDR400 Registered SDRAM, 200MHz, 3-3-3-8
Graphics Driver: NVIDIA ForceWare 83.40

Compared to the GeForce 6800 GS running on an nForce4 PCI Express system, with an AMD Athlon 64 FX-57 CPU, the BFG 7800 GS on AGP with FX-53 is ahead by over 80 per cent at 1280x1024 - the clocks and shader unit set-up see to that.

In Splinter Cell, the gains aren't as massive as they are with Quake 4, but more than 30% per cent extra performance is had at 1280x1024.

Compared to a recent test of a Radeon X1600 XT on PCI Express, with Athlon 64 4000+ (equal to our FX-53 in the AGP system), the BFG 7800 GS OC is ahead by over 50 per cent in our Far Cry benchmark.

While we're cross comparing to PCI Express systems with different CPUs and drivers, invalidating the numbers in a scientific sense, you can see the performance potential locked in to GeForce 7800 GS on AGP. It seems nicely ahead of anything readily available on AGP, brand new from retail.