[SOLVED] Does a PCIe 2.0 x4 capture card get more from a 3.0 x8 slot?

[F34RTEHR34PER]

So, this is a problem that Gigabyte and AverMedia hasn't come back with a solution. The AverMedia Live Gamer 4K promtoes 4K HDR 60fps capture if system specs are met.

This is what I'm using:
AMD Ryzen 7 3700X
32GB Crucial Ballistix LT 3000 MHz DDR4 RAM
Zotac RTX 2070 Super
Gigabyte Aorus x570 Pro Wifi
AverMedia Liver Gamer 4K Acer
Predator XB271HU bmiprz 27" WQHD (2560x1440) NVIDIA G-SYNC IPS Monitor
BenQ EW3270U 32 inch 4K HDR Monitor with FreeSync
Xbox One X

When put in the x4 slot, I can't get passed 54.92fps using P010 decoding (which is what Avermedia uses for the hdr). If I switch it to the x8 slot, it reaches 60fps without a hitch.

 

[Eximo]

Well, I suppose the question is what is running each slot? If the 8x one is from the CPU, that would improve performance rather than having it compete with your other devices for bandwidth.

 

[F34RTEHR34PER]

My board is the Gigabyte Aorus Pro Wifi.

1. 1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x16 (PCIEX16)
2. 1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x8 (PCIEX8)

and for the chipset

1. 1 x PCI Express x16 slot, supporting PCIe 4.0*/3.0 and running at x4 (PCIEX4)
   * For 3rd Generation AMD Ryzen™ processors only.
2. 2 x PCI Express x1 slots, supporting PCIe 4.0*/3.0
   * For 3rd Generation AMD Ryzen™ processors only.

 

[Eximo]

Well I think that answers that. Direct to CPU is the better performer. That could just be down to the chipset's need to handle other tasks or simply more noise and data resends on those lanes. Hard to say.

Only downside to using the CPU slot is that it will run your GPU at 8x as well.

 

[F34RTEHR34PER]

Well I think that answers that. Direct to CPU is the better performer. That could just be down to the chipset's need to handle other tasks or simply more noise and data resends on those lanes. Hard to say.

Only downside to using the CPU slot is that it will run your GPU at 8x as well.

Yeah, I tested that out, even knowing already that it's a 1x16 or 2x8. While doing a capture, I played FH4 with max settings at 1440p. Without the capture card in use, but it is in the 8x slot, I easily get 60+fps with 73% GPU use. With the capture card in use, I get 55-58fps with 95% GPU use.

I wonder since it's a x4 card in an x8 slot, it resorts to x4. Does that mean my x16 is now a x12? lol I know it's most likely not, but still... lol

 

[Eximo]

Lane switching doesn't work that way, no. So it would still be 8x/8x. The card would be limited to 4x, since I imagine that is the pin count it has. But the controller has the free bandwidth to deal with it at maximum bandwidth it seems. Though, again, that could just be the overhead and latency inherent to using the chipset lanes.

 

[F34RTEHR34PER]

Lane switching doesn't work that way, no. So it would still be 8x/8x. The card would be limited to 4x, since I imagine that is the pin count it has. But the controller has the free bandwidth to deal with it at maximum bandwidth it seems. Though, again, that could just be the overhead and latency inherent to using the chipset lanes.

Yeah, my hopes weren't too high on my 12+4 lol. So, I wonder if there's anything I can do to keep this card in the x4 slot, and increase the performance so that I don't have to use the x8 slot. It's Gen 2 card. If it was Gen 3 or 4, wouldn't that increase the bandwidth it takes from that x4 Gen 3.0 or 4.0 supported slot?

 

[Eximo]

It will be capable of operating at a faster transmission speed, yes. Doesn't mean it would perform any better unless the hardware on the card could also run faster.

If it were still going through the chipset it might still run into the same issue. There is a limit to the bandwidth available between the chipset and the CPU, and everything else on the bus has to communicate through that as well.

 

[F34RTEHR34PER]

Understood and thanks a ton for all the help. I'll get with Gigabyte and see if they can give me an idea of something that can help, or if it's just where it's going to be and I'll have to use the x8 slot.

 

[F34RTEHR34PER]

Just as an update...

AverMedia got back with me. They were able to reproduce the problem. They said that an add-on card shared the payload size with the capture card, 128Mb, and they disabled that card, and everything worked normally after that. The card needs a 256Mb payload size.