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PCI-Express 4.0 Performance Scaling with Radeon RX 5700 XT

W1zzard

W1zzard

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PCI-Express 4.0 has been one of the main new features prominently brandished on the product boxes of both the 3rd generation Ryzen desktop processors and Radeon RX 5700 series graphics cards. We examine the performance impact of running these cards on older generations of PCIe.

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Soo, not really game changer. How about CF, oh wait did navi even support that? Is there any mgpu dx12/vulkan titles out there?
 
Thanks for the review, as we can see here, no difference at all when bandwidth is plenty, even the archaic pcie2.0 still holds true to that.
 
This was always going to be nothing more than a marketing bullet point sadly. It will be more interesting in the coming years when much faster cards hit the market.
 
People are so ignorant and uneducated. PCI-E 4.0 isn't about the GPU performance just yet, its mostly about AMD's infinity fabric on the CPU side being better utilized and faster connections all round for the CPU. Second benefit is much faster SSD's, in fact double speed SSD's over the current generation.
 
tfdsaf said:
People are so ignorant and uneducated. PCI-E 4.0 isn't about the GPU performance just yet, its mostly about AMD's infinity fabric on the CPU side being better utilized and faster connections all round for the CPU. Second benefit is much faster SSD's, in fact double speed SSD's over the current generation.
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I guess thats one way to look at it. On the other hand, I personally dont really care either unless it improves FPS.
 
This is going to be huge in the server/storage world, like stupidly huge, as the SSD's are just getting bigger, bandwidth has to be able to keep up. Double the capacity is amazing.
Gaming results, however, as as everyone else predicted (knew, actually).
 
So no productivity tests then
 
Fatalfury said:
so much for PCI 4.0...
no wonder they 5.0 will come sooner or later..
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That is because Data Centers want more bandwidth for storage /network etc, there is nothing to do with gaming GPUs.
 
100 $ more for motherboards with completely useless technology. Great stuff!
 
This test indicates nothing.
What is really important is a frametime graph to see if there are any annoying frametime spikes.

Guys, seriously - why did you remove the minimum fps results from your tests? Average fps is nothing without 0.1% and 1% fps. Just sad.
 
ORLY said:
This test indicates nothing.
What is really important is a frametime graph to see if there are any annoying frametime spikes.

Guys, seriously - why did you remove the minimum fps results from your tests? Average fps is nothing without 0.1% and 1% fps. Just sad.
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What's sad is the number of people who aren't capable of performing reviews posting ideas that **don't matter** if there is an issue with frame times and lag caused by PCIe3.0 doubling the bandwidth won't change that, as doubling the bandwidth does nothing for latency, or additional latency from CPU, driver, or cache misses.
 
The main win for PCIe 4.0 is doubling the lanes, and faster SSD performance. So yes, the graphics card doesn't really benefit from 4.0 x16, but you could run a graphics card in 4.0 x8 and still have 8 lanes directly wired to the CPU. People always talk about how Intel processors are limited in the consumer sphere to too few lanes and have to go over the DMI link, switched, for some of their devices. Well, here you go. Effectively double the lanes of Intel's chips on an x570 now.

The main benefit of these GPUs running 4.0 is that they can utilize x8 links at effectively PCIe 3.0 x16 bandwidth.
 
danbert2000 said:
The main win for PCIe 4.0 is doubling the lanes, and faster SSD performance. So yes, the graphics card doesn't really benefit from 4.0 x16, but you could run a graphics card in 4.0 x8 and still have 8 lanes directly wired to the CPU. People always talk about how Intel processors are limited in the consumer sphere to too few lanes and have to go over the DMI link, switched, for some of their devices. Well, here you go. Effectively double the lanes of Intel's chips on an x570 now.

The main benefit of these GPUs running 4.0 is that they can utilize x8 links at effectively PCIe 3.0 x16 bandwidth.
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Exactly, the GPU isn't benefitting in any real or tangable way, the peripherals like ssds, and eventually WAN will benefit. The comments are almost NPC level junk about the reality of it though.
 
Ok, but what about lows ie. 1% of lowest framerate? Does PCIe 4.0 helps with frame drops? Avg values are important, but lows are also!

As others noted, please test SSD performance using PCIe 4.0!
 
RainingTacco said:
Ok, but what about lows ie. 1% of lowest framerate? Does PCIe 4.0 helps with frame drops? Avg values are important, but lows are also!

As others noted, please test SSD performance using PCIe 4.0!
Click to expand...

PCIe bandwidth shouldn't change anything with lowest 1% frame rates, it's a question of latency and driver maturity. It's like having a 16 lane superhighway where more cars can fit but they still have to go the speed limit.
 
Thanks for the review. I was wondering if this would be much of a difference maker. My gut told me no, but then AMD demoed the 5700XT on a PCIe 4.0 platform and made it a talking point. Considering the upper-mid-range nature of the card, I don't see how PCIe 4.0 could really make a significant difference. Even if there is a synergy to be had, I just don't see it making it into ver 1.0 motherboard, CPU, and GPU designs. Not enough saturation to make it a selling point at the GPU level.

Could you try some compute workloads and see how that does?
 
So where are the results for PCI-E 4.0 16x ???
 
Awesome review would be interesting to do more of a full system test to see if you could 'clog up' the pipeline with multiple gpus faster ones like 2x2080ti and m.2s in raid0 and run a timed sequence of tests maybe it will compound the differences.
 
bobbygamer said:
Awesome review would be interesting to do more of a full system test to see if you could 'clog up' the pipeline with multiple gpus faster ones like 2x2080ti and m.2s in raid0 and run a timed sequence of tests maybe it will compound the differences.
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there should be no difference, the lanes are not shared
 
I have a feeling that these games are ALREADY over-optimized (i.e. dumbed-down) for NVidia cards with their compressed textures. PCIe 4.0 should allow the system to sideload some amazing, vivid, detailed textures, when AMD gets to 50% marketshare, which is never. In the meantime the 3D experience for everyone will be poorer because NVidia profits more.
 
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