PCI 424 Card Slowing Down SATA RAID

[smallisland]

I wondered if others have experienced this issue.

With my MOTU PCI 424 card installed in my system it dramatically slows down the access speed to my e-Sata RAID set up!

I use a G5 Dual 2.5 Ghz PowerPC for video and audio work.
I need to use two of the 3 PCI-X slots for an AJA/KONA 2 HD Video Card (for HD Video output) - and a Sonnet Technologies Tempo SATA X4P card to connect to my 5 x 500 RAID enclosure. When I introduce the MOTU PCI-424 card into any of the slots (in any configuration) - my RAID performance drops from over 200Mbps to around 80Mbps!!

I understand that two of the PCI-X slots share their performance and will perform to the "speed" of the lowest common denominator (although I have found it to be the case in any configuration of positions I try!!)

Is the PCI-424 just a "slow card"?

It's a bit impractical for me to open up my machine and install the PCI-424 card each time I want to use it with my 2408, so I have been going firewire to a Traveller. However, I really miss 24 ADAT channels (vs. 8 via the Traveller)!

Any comments, thoughts, solutions.

Thanks so much for your assistance

[billruys]

Your PCIx raid controller probably runs natively at 66, 100, or 133 MHz. I would bet that the PCIx-424 card drops the bus speed down to 33 MHz as per the original PCI specification. Many cards that were PCI and then ported to PCIx, are PCIx compatible in voltage only (3.3v). They will force the PCIx bus to slow down to 33 MHz.

I'm not a mac guy, but if your Mac has more than one PCIx bus, you need to find out which PCIx slots are on which bus and try to get the raid controller and PCIx-424 card on separate busses.

[jborum]

Does anybody know how or where to find out which PCI slots share a common bus? I have all my PCI slots full, and it seems like it might benefit me to think carefully about which ones are sharing bandwith.