Dual eGPUS not working at the same time

[DanWise366]

Hi, wondering if anyone can help.

I do a lot of heavy 3D work so I purchased a liquid cooled 4090 rig (full specs in my sig). I have two Razer Core X's each containing a 4070ti. I can get windows to recognize each of them independently and they work great when rendering, but I can't get the both to work at the same time, windows thinks about it then neither show up. I've been searching for a solution considering bios settings, windows settings, NVidia driver settings and motherboard limitations. So far nothing I have looked at works. Don't suppose anyone else had had the same issue or has any useful ideas?! Thanks in advance.

 

[TonyCarter]

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[SpyderTracks]

eGPUs are not very efficient at the best of times, but I suspect there's a bandwidth limitation.

I take it you're using the 2 thunderbolt ports on the motherboard? I mean you're definitely not mistaking the right one of the three which is a USB C port?

Just separately to all this, I take it you're on a recent BIOS? If you haven't updated the BIOS as yet, don't do it without PCS approval as it may void your warranty.

 

[SpyderTracks]

Try this setting if you haven't already:

Go into the BIOS, Advanced, Thunderbolt (TM) Configuration and disabling PCIE Tunneling over USB4

Source:

https://www.reddit.com/r/ASUSROG/comments/146h33v

 

[DanWise366]

Thanks so much for the quick reply.

I am connecting to both thunderbolt ports yes (I just double checked). I haven't altered that BIOS settings that came with the machine. Just tried disabling the PCEI tunnelling setting but after reboot it failed to recognise either eGPU (tested them in turn - didn't connect or show up in the device manager), turning it back on means that they can both be seen again.

 

[SpyderTracks]

Thanks so much for the quick reply.

I am connecting to both thunderbolt ports yes (I just double checked). I haven't altered that BIOS settings that came with the machine. Just tried disabling the PCEI tunnelling setting but after reboot it failed to recognise either eGPU (tested them in turn - didn't connect or show up in the device manager), turning it back on means that they can both be seen again.

I would definitely suggest getting on the latest BIOS as that may well contain a fix.

Either way though, you need it for the recent Intel microcode update to limit the overvoltage that kills the processor.

I would start there, give PCS a call and get their approval to flash a BIOS update, they'll tell you which one they think is most appropriate

 

[SpyderTracks]

To be honest, I wouldn't bother particularly trying to troubleshoot this.

It's a desktop, not a laptop, so eGPU just makes no sense anyway. If it were me, I'd be pulling out the open loop setup, find a 420mm AIO to put on the CPU, then strap in each of the GPUs in a dedicated PCIe slot and go from there, you'd get SIGNIFICANTLY better performance even if you had both eGPU's working concurrently, eGPU's are only really effective for around 60 - 70% of the available performance of the GPU.

The 4000 series are so efficient, you really don't benefit all that much from watercooling even on the GPU, there's so much headroom even under air (like 20c) you're never really concerned about throttling scenarios like on previous generations.

 

[DanWise366]

Thanks for the recommendation about updating the bios.
A liquid cooled system made sense for me as under load a 4090 when rendering can be very loud and kick out a LOT of heat. Any extra GPU power helps speed up rendering (even factoring thunderbolt limitations). I can increase render times by around 25% with my 4070ti which is a big deal, plus I had the Razer boxes from my last setup so was minimal investment for the return!

Very much appreciate your advice and recommendations. Sure there will be a way to get them both working at the same time.

 

[SpyderTracks]

Thanks for the recommendation about updating the bios.
A liquid cooled system made sense for me as under load a 4090 when rendering can be very loud and kick out a LOT of heat. Any extra GPU power helps speed up rendering (even factoring thunderbolt limitations). I can increase render times by around 25% with my 4070ti which is a big deal, plus I had the Razer boxes from my last setup so was minimal investment for the return!

Very much appreciate your advice and recommendations. Sure there will be a way to get them both working at the same time.

Your call. eGPU's are intended for systems like laptops or a NUC, they’re not designed for desktops as you have no need for them as the PC is fully capable of dealing with the heat output (assuming you have a semi decent case but on the water-cooled options, they only have expensive high end cases). That motherboard has space for 2 GPUs both at x16, one 4070ti and 4090 actually in the PC would give far more rendering power than 1 x 4090 and the 2 x 4070ti in eGPUs.

Your setup is not unusual with multi GPU's for rendering, plenty of people use that kind of setup absolutely fine without closed loops. As said, the generational gains of RTX, let alone the step up to the efficiency of the 40 series means that concerns of those natures are no longer relevant as they used to be.

I think you'd be really surprised if you just plugged the 4070ti's into the spare PCIe lanes at how quiet the system is. Heat is irrelevant in that level of case, that's exactly what they're designed for.

At the moment you're severely hampering the capabilities of the system for a cooling solution that isn't really necessary. The CPU requires a robust cooling solution but a 420mm AIO would do a similar job.

 

[Paul1964]

Thanks so much for the quick reply.

I am connecting to both thunderbolt ports yes (I just double checked). I haven't altered that BIOS settings that came with the machine. Just tried disabling the PCEI tunnelling setting but after reboot it failed to recognise either eGPU (tested them in turn - didn't connect or show up in the device manager), turning it back on means that they can both be seen again.

Thunderbolt works for eGPUs by carrying 4 lanes of PCIe so disabling it would have the effect of rendering the eGPUs invisible.

Spider's advice was specifically about USB4 which can also carry 4 lanes of PCIe. Maybe this was to prevent any conflict over the similar (but not exactly the same) protocols.

Either way - the advice to add one of the 4070tis onto the actual motherboard is the far better option. The other 4070ti should fetch a good price on eBay. 🤑