So, I was asked to clarify my setup in another thread.

Ny functioning GT1050ti is Slot 4. The one hat does show up in Linux is in Slot 12.

Both processors are  E5-2630's and I have 96GB of RAM.

Hello OP, a few suggestions for troubleshooting.  Check in BIOS for any obvious settings that needed to be enable/disable

Swap the card around for testing and you can also test one card on slot 2, one on slot 4.

Supposed you figure it out and fix the problem, if your upgrade goal will be RTX3070, it shouldn't be problem.  Just remember to remove the retention bar of the handle as it could block the clearance of some cards.  If you choose RTX3090 or RTX4090, most likely you must mod the cover panel and for certain, you must have enough power (rails) PSU.

If you just want CUDA cores, get 3 single slot cards, like Quadro P4000.  They are dirt cheap now.

Thanks for the reply. Still looking at my options.
Shouldn't the 1300W PSU be enough for at least a 3090?
I think the T7910 already has some rails for power.

I half wonder if I might not be better off a Thunderbolt 3 card and external case with PSU for a 4090.

Since I maxed out with PCI 3.0 speeds anyway, how much of a performance hit would I get with TB vs PCI directly.

GPU's are getting so big and power hungry their going to start being like NAS!

I think that the header on the T7910 mobo supports TB2, not TB3.  Can someone confirm?

Also, the 1300 W PS should be quite adequate for the 3090.   I have a 2080 Ti (250W) and dual E5-2699 v4 (145W each) for a total of 540W between cpu and graphics card.  The 4090 (450W) and dual E5-2630s (85W each) add up to 620W.   Pretty sure that the rest of the rig doesn't take anywhere near 700W.   

A 1300w PSU should be enough, just remember to use separate 8-pin cables connecting to power distribution board.  The T7910 supports thunderbolt 2 and the thunderbolt AIC needs to be installed on slot 3, which is a PCIe gen.2 slot.

WizardOfBoz2 

"I have a 2080 Ti (250W) and dual E5-2699 v4 (145W each) for a total of 540W between cpu and graphics card. "

I'm looking to upgrade those processors to E5-2699 or E5-269 v4 at some point so that would top me at 740 watts. Still might be able to host a3070 on top of that!

Timed out on edit.
Should have read...

"I'm looking to upgrade those processors to E5-2699 or E5-2696 v4 at some point so that would top me at 740 watts. Still might be able to host a RTX3070 on top of that!"

Unless someone figured out a BIOS hack for the T7910 so e5 V3 processors can be boost clocked all the time like on cheap X99 board. Then I might go with 2x E5 269x V3 and live with fewer cores for higher clocks.

Wow!! I can't belive how stupidly convoluted it is use Thunderbolt on anything.
Why the [expletive deleted] do I have to route a DisplayPort through the Thunderbolt card?

I want to hook up an eGPU. I don't want to pass an internal GPU to a monitor.

I'm beginning to think we need a PCI 3.0 card hooked up to a full x16 wide slot with some Intel Celeron that also has the latest TB on it, and just use it as a I/O controller.

PCI 3.0 has  a theoretical limit 32GBps. I got a Dual XEON system so I would have enough I/O lanes to do anything I needed. But I don't PHYSICALLY have access to the slots because the GPU's are now blocking the physical slots. If we could just use a low power celeron that has TB support built in ,and make it take up a single PCIe slot, it would be better than what we are doing now.

It looks like my best bet is to investigate water cooling options for my T7910.

There are 2 card wide Water Cooked RTX4090's. One of them will beat 3 Quado RTX A5000 by almost 2x.

Just in case any of you can help - I have 2 GTX 1080 cards with HB Bridge installed in my T7910, and the Control Panel is not showing SLI.  Am i stuck to selling both cards and only being able to use 1 card?  Anybody know if Nvidia Profile Inspector can be configured to bypass the limitation?

Best CPU for gaming rig is E5-2689 V4 - 10 core and run up to 3.8Ghz.  I am using E5-2643 V4 with 3.5Ghz and  system works really well.