MP 1,1-5,1 Mac Pro 5.1 struggling with PCEi adaptor in slot 2?

[JoeStrummer]

So I tried to speed up up my Mac Pro 5.1 by installing an "IO Crest IO-PCE2824-TM2 (Syba SI-PEX40129)" PCEi adaptor fitted with 2x Samsung 970 Pro 512mb blades. Using one blade as a boot volume (Mojave). Everything works great, getting speeds of around 2400/2500mbs.

The problem is that fitting PCEi adaptor to slot 2 means it is almost touching my Radeon RX58o gpu which is in slot 1. I used thermal pads as spacers but still extremely tight. Monitoring the temps didn't show up anything outrageous on cpu or gpu operating temps. But...the whole system seems sluggish and sticky. Lots of spinning wheels. A couple of system stalls/freezes. My feeling is that the gpu cannot really operate properly without proper airflow? Its just too tight.

So I have now put the PCEi adaptor in slot 3. Left slot 2 empty for airflow. But slot 3 is slower (less wide) and am only now getting around 1300/1400mbs. But I reckon I will try it that way, rather sacrifice some speed for a smoother more reliable system.

Also had to sacrifice a SSD which was originally in slot 3.

Are there any ways around the issue of not enough space between PCEi slots on the Mac Pro 5.1's?

 

[tsialex]

So I tried to speed up up my Mac Pro 5.1 by installing an "IO Crest IO-PCE2824-TM2 (Syba SI-PEX40129)" PCEi adaptor fitted with 2x Samsung 970 Pro 512mb blades. Using one blade as a boot volume (Mojave). Everything works great, getting speeds of around 2400/2500mbs.

The problem is that fitting PCEi adaptor to slot 2 means it is almost touching my Radeon RX58o gpu which is in slot 1. I used thermal pads as spacers but still extremely tight. Monitoring the temps didn't show up anything outrageous on cpu or gpu operating temps. But...the whole system seems sluggish and sticky. Lots of spinning wheels. A couple of system stalls/freezes. My feeling is that the gpu cannot really operate properly without proper airflow? Its just too tight.

So I have now put the PCEi adaptor in slot 3. Left slot 2 empty for airflow. But slot 3 is slower (less wide) and am only now getting around 1300/1400mbs. But I reckon I will try it that way, rather sacrifice some speed for a smoother more reliable system.

Also had to sacrifice a SSD which was originally in slot 3.

Are there any ways around the issue of not enough space between PCEi slots on the Mac Pro 5.1's?

Some people use the GPU with slot-2, blocking access to slot 3, and the switched card with slot-1. This way you lose a slot but have optimum throughput. That's what I did.

There isn't a perfect solution, you have to lose something.

 

[startergo]

I may be wrong but installing a 2.2 slot card in slot 2 will waste 2 slots the same way if it is installed in slot 1 which is a double slot unless of course you don't populate all hard disk slots. I hate these 2.2 wide cards.

 

[tommy chen]

I have installed some RX580 and I noticed that
the 4.1er has less room to move the PCIe slot2 is more than original 5.1er


but you can see that the 5.1 has more room
the cards are the deepest pressed to tighten the screws
and therefore also the holes could be different

but also on the far left you can see a difference

the insulation plate could be of different heights, but i haven't measured that yet.

 

[JoeStrummer]

Some people use the GPU with slot-2, blocking access to slot 3, and the switched card with slot-1. This way you lose a slot but have optimum throughput. That's what I did.

There isn't a perfect solution, you have to lose something.

Thanks for this - good idea worth trying

I can report that after moving the PCEi adaptor card from slot-2 to slot-3 - thereby giving the gpu space to breath - the whole system does feel smoother and less lags! But will also try above suggestion, thanks