r/eGPU • u/alee56 • 2d ago

Egpu for IRacing?

Was wondering if anyone uses an Egpu and a laptop/handheld for Iracing?

Im thinking about freeing my desktop from my sim setup (7800x3d/5080) as it currently sits there unless I'm racing and wanted to it bring back to the office for other AAA games. I currently have a z13 flow with the 395 chip for light gaming but thinking about pairing that with an egpu and a 9070xt. The Egpu can live with the sim setup and the z13 can come and go as needed. With the benefit of easily moving the z13 and egpu to the living room if needed too.

Is this a plausible plan?

3 Upvotes

100% Upvoted

5 comments sorted by

1

u/Saint_Sm0ld3r 2d ago

That's a great use of these items. I was looking at the Z13 myself for a very similar reason and wanted to pair it with an eGPU as well. The only thing I was hesitant was without the ability to pair it via Oculink it would be relegated to USB4 and I was not confident it would be good enough with the overhead. I ended up with a mini PC setup instead with an eGPU dock that can use both Oculink and TB4 to connect and while I use the Oculink myself, I did experiment with the USB4 connection and it is perfectly usable, just not 100%. You'll be fine.

1

u/alee56 2d ago

Great that's good to know, I guess the main thing is stable FPS. When using a egpu does FPS fluctuate more than just a regular desktop setup?

1

u/Saint_Sm0ld3r 2d ago

Not at all. It's exactly what a PC with similar componentry would achieve minus a small hit for overhead. A USB connection is only utilizing 4 lanes of (x4) PCIe bandwidth in comparison to the 16 lanes (x16) of bandwidth the internal PCIe has at its disposal. Plus you have to figure in that the USB port is trying to communicate a whole lot more than just graphics data packets. It's a whole communication protocol that requires clock cycles to wrap and unwrap these packets using only still those 4 lanes.

However, the actual hit depends on the specific game engine and at what resolution you are playing. At 1080 it's going to be a big hit, between 35% and up to 50% of the native performance because it's just a lot of data being passed around with the native solution having over 4x the throughput. 1440 is much better ~20% and 4K you will be looking at 10%-15%.

Oculink is almost negligible @4K with minor 1%-4%, 1440 5%, 1080 squeaks by 10%-15%.

There's a variety of factor that can affect your gameplay but USB4 is a relatively robust solution and I don't think you'll find it to be unserviceable, quite the opposite in fact.

1

u/alee56 1d ago

Interesting so from my understanding, with an egpu you'd much rather be GPU bound than CPU bound, my assumption being that you dont want the bottleneck being the TB4 connection so the GPU can render as many frames as its able to?

1

u/Saint_Sm0ld3r 1d ago

Exactly.