data speed worries using an eGPU

[lpriemueller]

I'm considering downsizing my PC to GEEKOM Mini IT13 and have been brainstorming ideas on how to still hold on to my GPU. I have found  USB4 to PCIe 4.0 x 16 "adapters" which on paper should allow me to connect my GPU to the mini PC using one of its USB4 ports. My worry is that going over USB will be a significant bottleneck for the GPU than if it was directly connected to the CPU via PCIe. So are my worries legit? or am I getting caught up over nothing? 

 

 

https://www.geekompc.com/geekom-mini-it13-mini-pc/

 

https://www.aliexpress.us/item/3256806072109615.html?aff_fcid=1036bbbb26464c1ca6f2da0755c57bf9-1713125800942-09819-_DcZa2q1&tt=CPS_NORMAL&aff_fsk=_DcZa2q1&aff_platform=shareComponent-detail&sk=_DcZa2q1&aff_trace_key=1036bbbb26464c1ca6f2da0755c57bf9-1713125800942-09819-_DcZa2q1&terminal_id=be23e791b0364c58a200441883599bd1&afSmartRedirect=y&gatewayAdapt=glo2usa4itemAdapt

[matt0725]

there is some performance loss when using those EGPU setups, but how much depends on how powerful your GPU is to begin with. slower GPUs experience less performance loss.

[ki8aras]

31 minutes ago, lpriemueller said:

I'm considering downsizing my PC to GEEKOM Mini IT13 and have been brainstorming ideas on how to still hold on to my GPU. I have found  USB4 to PCIe 4.0 x 16 "adapters" which on paper should allow me to connect my GPU to the mini PC using one of its USB4 ports. My worry is that going over USB will be a significant bottleneck for the GPU than if it was directly connected to the CPU via PCIe. So are my worries legit? or am I getting caught up over nothing? 

 

 

https://www.geekompc.com/geekom-mini-it13-mini-pc/

 

https://www.aliexpress.us/item/3256806072109615.html?aff_fcid=1036bbbb26464c1ca6f2da0755c57bf9-1713125800942-09819-_DcZa2q1&tt=CPS_NORMAL&aff_fsk=_DcZa2q1&aff_platform=shareComponent-detail&sk=_DcZa2q1&aff_trace_key=1036bbbb26464c1ca6f2da0755c57bf9-1713125800942-09819-_DcZa2q1&terminal_id=be23e791b0364c58a200441883599bd1&afSmartRedirect=y&gatewayAdapt=glo2usa4itemAdapt

while the adapter accepts a 4.0 x16 signal from the gpu, it only spits out a 3.0 x4 signal over the usb4 connection, so expect about half the performance you would usually have (performance loss dependent on gpu and resolution, but definitely a significant hit in any case)

[matt0725]

11 minutes ago, ki8aras said:

while the adapter accepts a 4.0 x16 signal from the gpu, it only spits out a 3.0 x4 signal over the usb4 connection, so expect about half the performance you would usually have (performance loss dependent on gpu and resolution, but definitely a significant hit in any case)

you would experience half the performance if you were fully saturating a 4.0 connection, which no GPU does. Most GPU's don't saturate a 3.0 connection currently. maybe a 4090 or 7900xtx would see a big hit, but even then it would certainly not be 50%

[lpriemueller]

I was planning on using my Quadro RTX 4000 for this build, but with the performance losses I definitely don't think it is worth it. Thank you all for your input. 

[ki8aras]

10 hours ago, matt0725 said:

you would experience half the performance if you were fully saturating a 4.0 connection, which no GPU does. Most GPU's don't saturate a 3.0 connection currently. maybe a 4090 or 7900xtx would see a big hit, but even then it would certainly not be 50%

as i said, usb4 carries a pcie 3.0 x4 signal, so you only have to saturate that to see a performance loss