I successfully operated the ARC-1210 in the second PEG slot
of an ASUS A8N-SLI Deluxe in x1 and x8 mode. At x8 mode,
the sustained transfer rate was 155 MByte/sec (with a four
disk RAID5 setup). In x1 mode, performance drops to
A couple of month ago, i switched to an ASUS A8N-SLI Premium
(because of passive cooling and the PCIe x4 slot). The two
PEG slots are populated with 7800 GTX cards (for a tripple-head
setup). I needed to cut of the end of x4 slot so that the ARC-1210
(which is an x8 card) fits in. Unfornuatly, there is only one pair of
lanes connected to the x4 slot, so that the controller only works in
x1 mode (only 140 MByte/sec), but that's not a too big issue for me.
Hopefully, there are soon new AMD64 mainboards out with plenty
of configurable PEG slots, something link this:
Anyway, an open-ended "true" x4 slot should be good enough.