PCIE 424 card in a Mac Pro early 2008 intel- X4 or X16 PCIE slot?

[Renaissance Man]

I currently have a MOTU PCIe 424 card in the top 4X slot on the Mac (slot 4). Does the PCIe 424 card REQUIRE a 4X slot or a 16X slot? I've experimented with both and it doesn't seem to make any difference. I've searched MOTU's site and can't find any reference as to what slot the MOTU PCIE 424 card requires

The reason I ask is that after recording and stopping, it can take several minutes before it will play (apparently while it writes the data to the slow 7200RPM drive and renders the tracks). Further, when switching between projects, DP will almost always crash when the current project closes. AND, it takes a long time to load project audio from the work drive when opening a project.

Observing the Mac activity monitor while recording a 48 track project in DP, the memory usage is right around 4GB (at peak) of the available 16GB of RAM, and the processor usage is right around 54% (at peak). The activity monitor shows disc usage (of the 7200 RPM project work disc) is very high (while reading AND writing) and appears to be the choke point.
I'm thinking I might add a OWC Accelsior S + OWC Mercury Electra 6G SSD as my work drive, but it requires a 16X PCIe slot in order to get the full speed capacity out of the SSD.

IF the PCIe 424 card only requires a 4X slot, I can use the available 16X slot (slot 2) for the SSD. If the MOTU PCIe 424 card DOES require a 16X slot I might just add a 3G SSD to one of the drive sleds and use it as my work drive.
Just trying to squeeze some more life out of my set up, and alleviate a few crash headaches...

[mikehalloran]

The last G5 cheese graters had PCIe slots. These were the Macs that the 424e card was designed to fit. Likewise it fit all Intel Mac Pros through the 5.1 in 2012.

[Renaissance Man]

What I'm asking is: what slot on the Mac Pro early 2008 intel motherboard does the 424 card require. A 4x slot or a 16X slot?

[HCMarkus]

Pretty sure 4x. If it FITS in a 4x slot, it should work there.

PCIe boards can fit into slots designed for their lane configuration or higher. Plugging a x4 PCIe into a x16 slot (up-plugging) is acceptable. The opposite (down-plugging) is not physically supported

.

[mikehalloran]

What I'm asking is: what slot on the Mac Pro early 2008 intel motherboard does the 424 card require. A 4x slot or a 16X slot?

I already answered your question. Those three G5s with PCIe slots were 4 Lane. The 424e card was designed to fit those.

https://everymac.com/systems/apple/powe ... slots.html

Likeise, the 424e card fits all Intel Mac Pros.

https://everymac.com/systems/apple/mac_ ... slots.html

MOTU has never differentiated some PCIe slots as not working in any of the above computers. If they do know anything differently, that bit of info never made it here—it's certainly not found in a tech bulletin search.

What we do know is that these cards do not work in 3rd party boxes connected to Macs, 2019 nor 2013 Mac Pros because of firmware issues. There is no workaround.

[Renaissance Man]

Thank you. I learned something today. I didn't know they were called lanes. I wasn't even aware that the PCIe slots were different and what the differences were until recently. Now I understand 4X is 4 lane and 16X is 16 lane. I don't really know what that means except the obvious inference that the 16 X has a lot more data throughput and/or speed, and the voltages can be different. I appreciate your patience! The older I get the more awareness I have of how little I know. Thanks again

[Renaissance Man]

Since I now know the PCIe 424 card is made for a 4X slot, I ordered a 6G SSD with PCIE adapter from OWC for my only available 16X slot. Hopefully it will cure the disc read/write choke point I've been experiencing, and I can squeeze a little more life out of this 16 year old machine.
In the meantime I will keep my eye out for a 2012 12core 3.33mhz machine (that still supports the PCIE 424 card) like Markus suggested in my 'New Mac Pro and PCIe card compatibility' thread .That will give me a little more processor muscle and advance past El Capitan to a more recent Mac O.S.
I'm not quite ready to dump My 4 MOTU interfaces yet if I can get away with it.

[Renaissance Man]

Today I received and installed the 1TB 6G SSD with PCIE adapter in my early 2008 8core Intel mac. Went in easily- all I had to do was format the drive after start up. Unfortunately it didn't help the crashing when I open a new project (without first closing the previous one). It does load the projects more quickly. When I record many simultaneous tracks (say 24 or 32 at a time) it seems as if it takes less time to process/render the tracks after I hit stop. In any case, I'll be using it as my work drive moving forward.