There was the known problem when using the PCI Express 2.0 compliant 8800 GT or 8800 GTS 512 in some motherboards with PCI Express 1.0a slots. The card would not produce any display image, but the computer would often boot (with the video card's cooling fan spinning at a constant 100%). The incompatibility was confirmed on motherboards with VIA PT880Pro/Ultra, Intel 925 and Intel 5000P PCI-E 1.0a chipsets.
The board in question (ASUS A8BN-LE) has an ATI IXP 400 chipset. I'm probably pairing it with a GeForce 610 to keep costs as low as possible.
While we're at it...
Will the 32 bit 512mb version output 1080p video without choking to death? I hear these cards aren't quite as good as the HD5450, which is what I'd use if it wasn't pcie 2.1. I have 2 of these and they do their job just fine (this rig will never game anything heavier then NES roms and is mostly for watching movies on a 1080p television -- typically not 1080p files themseleves).