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can you connect the cards to a working PC?
if so, use GPUz to find out what the card is?
if not are there any stickers on the other side giving a clue to its idenity?
Edit: pretty sure the ati card is an x800, might be an x800xt or x850, not sure. The nvidia card might be a 6600 of some kind. If i am correct then the ati card is more powerful but the nvidia card supports smartshader 3 which the ati card doesn't.
Best double check, but nvidia card looks like the "NVIDIA QUADRO FX1300 PCIE 128MB DUAL DVI 8973 P268 TVO"
The ati card no idea as to model
Would hazard a guess the ati may have the edge due to twin slot and large fan/hs and what looks like extra power socket (top right)
Sorry not much help