PCI-E link speed on Gigabyte GA-MA790FX-DQ6 with 2 HD3870

[kybeer]

I'm running a GA-MA790FX-DQ6 with 2 HD3870 and getting different PCI-E link widths in GPU-Z (v. 0.3.0) for my two cards. Regardless of GPU activity (it seems) GPU1 is using 4x speed and GPU2 16x speed! I can confirm it with CPU-z. The 3870s are in the blue PCI-E slots, the ones to use in dual GPU Crossfire setup according to the MB manual.

What is controlling the width? I does not seem to affect performance though.

I'm using the latest motherboard BIOS (F6b), and have tried a couple of different Catalyst drivers.

Systemspec:

Phenom 9500 @ 11x240 = 2643mhz
8gb 800mhz DDR2
GA-MA790FX-DQ6 rev 1.0
2x Sapphire HD3870 GDDR4 (no OC)
Windows Vista x64