P6X58D-E, PCIE x16 slot #3, RAID cards ?

Anyone here with a P6X58D-E or Premium successfully running a controller card in PCIE x16 slot #3? Having some weird problems on a P6X58D-E with getting raid cards running in PCIE x16 slot #3.

Cards I've tried in x16 slot #3 are only detected on cold boot. Not detected on a restart.

Tried forcing x8 + x8 on slots #2 and #3 through BIOS (PCI Express Selector), but no success.

I have a 5770 in x16 slot #1. RAID cards I've tried so far are x4 and x1.

Cards seem to run fine in x16 slot #2. But I need slot #3 to work too... TIA for any feedback/insight.

I'm curious as to why you're not using the built-in Intel ICH10R controller for your RAID setup?

I use multiple machines for video editing and footage is on mobile port-multiplier external enclosures. Data format is dependent on specific RAID cards that are used on all machines and same cards must be used on all machines. Bottom line, the PCIEx slots need to work. I just RMA'd the board, if this is "working as designed" and all the P6X58D-Es are like this, unfortunately will need to use another mobo.