X38 and Areca cards

[IanB]

isn't that slot working ONLY at 4X?...i can't remember since i do not have the board any longer.

Should that matter? A PCIe x1 link allows 2Gbits/s or 250MBytes/s (in both directions simultaneously) allowing for signalling overhead. A x4 link is therefore equivalent to about 8 x 120MBytes/s which is the maximum bandwidth for the fastest current disks (thanks to Wikipedia for this link: http://www.tomshardware.com/2007/11/...ng/page9.html). Are you hanging more than 8 disks off such a card? If not, x4 is plenty.

Under 9 disks, I'm pretty sure you'll hit the internal bandwidth limit of the card (unless it's a seriously expensive high-end one) before you hit the limit of the PCIe slot. This was shown graphically in Dominick32's recent review of Mtron SSDs.