Latest update:

After figuring out how to use OSX86Tools to update the EFI strings for 9800 GTX+, I checked the Hardware Overview and noticed this:

Model Name: Mac Pro
Model Identifier: MacPro2,1
Processor Speed: 2.71 GHz
Number Of Processors: 1
Total Number Of Cores: 4
L2 Cache (per core): 256 KB
L3 Cache: 8 MB
Memory: 6 GB
Bus Speed: 533 MHz

I'm running the i7 920, so that information seems like it's completely wrong. Am I missing something, or did that get screwed up somehow?