pcie 3 x16 vs x8 for AMD 7900XTX

[Teammates go mid 2% slower]

Currently I have a GTX 1080 which is about 280 mm and fits in the first slot of my mobo Asus z490e. I am getting 7900XTX but there is not enough clearance in my case (Ultra Modded Q500L) because of the PSU. Wondering if running this bad boy in x8 pcie 3 is going to make a difference? I don't see any difference at 4k for gtx 1080.
Option 2 is to maybe get a pcie riser cable but I doubt the card will align in the case because it has to go in the pcie slot.

[Teammates go mid 2% slower]

Yes! unless someone wants to run an extension cable. A few weeks ago I had to invert the PSU because I had accidentally mounted the PSU intake inwards which was taking all the hot air above the graphics card and causing restarts

[Teammates go mid 2% slower]

https://imgur.com/a/NpAcNIM

[Bad 💀 Motha]

You could mod the case so the PSU mounts externally (on the Motherboard side)

Then setup the case for front air intake and top air exhaust maybe.

[Teammates go mid 2% slower]

this is when I built it 4 years ago. Since then I removed the mid fan and 3d printed a plastic panel with a 200mm phanteks fan

[Bad 💀 Motha]

Jeez what a poor design. Even my ITX Case from my old 4790K + 1080 Ti build had room for longer GPUs.

[r.linder]

Origineel geplaatst door Bing Chilling:

Origineel geplaatst door Bad 💀 Motha:

GTX 1080 Ti even, only needs PCIE 3.0 X8-X16

However 7900 XTX MUST be used on a PCIE 4.0 Motherboard + CPU; otherwise it will run at either X4 or X8 on PCIE 3.0; THIS will handicap such a GPU, as it really needs X8-X16 on PCIE 4.0 to open up its performance and usage; just like a RTX 4080 or 4090

really?
https://www.youtube.com/watch?v=v2SuyiHs-O4

That's with 16 lanes, 3.0 x16 is still fine for 4.0 x16 cards, it becomes a small loss when they're forced to run at 3.0 x8 bandwidth since the bandwidth is too little to give the full performance of the card, it's equivalent to 4.0 x4

Origineel geplaatst door Teammates quit 2% slower:

the issue is that I am going to put it in the second slot which is x8

If you can afford a 7900-XTX then you can afford a case that won't force you to do something stupid like this

[Teammates go mid 2% slower]

Im gonna try running a power cord extension and relocate psu to bottom, and see if that makes space xD

[Bad 💀 Motha]

Origineel geplaatst door r.linder:

Origineel geplaatst door Bing Chilling:

really?
https://www.youtube.com/watch?v=v2SuyiHs-O4

That's with 16 lanes, 3.0 x16 is still fine for 4.0 x16 cards, it becomes a small loss when they're forced to run at 3.0 x8 bandwidth since the bandwidth is too little to give the full performance of the card, it's equivalent to 4.0 x4

Origineel geplaatst door Teammates quit 2% slower:

the issue is that I am going to put it in the second slot which is x8

If you can afford a 7900-XTX then you can afford a case that won't force you to do something stupid like this

But again, most AMD GPUs since RX 5xxx series refuse to scale like that and will end up running at PCIE X4

[Dutchgamer1982]

was there not a post about this already.. that I already answered?

7900xtx has been tested at pcie 1 - 5 (all x16)

it had the same performance pcie 3 - 5
but at pcie2.. it lost about 3% performane at 1080p and 1440.. and 2% at 4k.

since pcie 2.0x16 is exactly the same bandwith as pcie 3.0 x8.. they likely will function the same all other things the same.

so yes running an 7900xtx at pci3.0 x8 will likely cost you 2-3% performance
when compared to pcie 3.0 x16

but the chance your cpu is costing you far more performance loss due it bottlenecking such a gpu is considerably higher
(what cpu are you using that still used pcie 3.0)

[Tonepoet]

It will make a difference but not much. From the Puget Systems Article Impact of GPU PCI-e Bandwidth on Content Creation Performance[www.pugetsystems.com] written by Evan Lagergren, August 30th 2023:

The real-time renderer we included in our testing is Unreal Engine 5.2, which is used in a wide variety of industries including game development, virtual production, and architecture visualization. As you might expect, reducing PCI-e bandwidth negatively impacts the average fps for NVIDIA and AMD GPUs. However, the effect is much more pronounced for the NVIDIA GPU, with an 8% total difference between PCI-e 3.0 x4 and 4.0 x16 compared to the 2% difference for the AMD GPU. When looking at sub-scores, we also see that the effect is much more pronounced for rasterized rendering performance, with 11% and 5% less performance for the RTX 4080 and RX 7900 XTX, respectively.

I reckon Unreal Engine 5.2 would be the most relevant benchmark shown for gaming and if we're saying you only get a 5% hit going down to P.C.I.E. 3.0 x4, then it's even going to be even less going to x8.

Another thing to note is that Minisforum mentions 7900 XTX compatibility with their DEG1[store.minisforum.com] E.G.P.U. dock and it uses a P.C.I.E. 4.0 x4 connection. Each generation of P.C.I.E. has double the bandwidth of the last, so 4.0 x4 should be equivalent to 3.0 x8. If Minisforum is so brazen as to mention such an expensive card for use on their dock, then I would the perf. results are good enough to merit it. Though they also mention a 4090, so maybe they're just off their rockers. Doesn't seem like it though.

However with those two points of data corraborating one-another, I really wouldn't worry much about the P.C.I.E. bandwidth.

(By the way, if anybody is interested in buying that dock I saw the coupon code GG30 on Google that takes $30 off of the price)

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Origineel geplaatst door Dutchgamer1982:

was there not a post about this already.. that I already answered?

7900xtx has been tested at pcie 1 - 5 (all x16)

it had the same performance pcie 3 - 5
but at pcie2.. it lost about 3% performane at 1080p and 1440.. and 2% at 4k.

since pcie 2.0x16 is exactly the same bandwith as pcie 3.0 x8.. they likely will function the same all other things the same.

so yes running an 7900xtx at pci3.0 x8 will likely cost you 2-3% performance
when compared to pcie 3.0 x16

but the chance your cpu is costing you far more performance loss due it bottlenecking such a gpu is considerably higher
(what cpu are you using that still used pcie 3.0)

Intel i9-10850k 10 cores 20 threads OC 5.1 Ghz all core

[Dutchgamer1982]

Origineel geplaatst door highly rated teammate:

Origineel geplaatst door Dutchgamer1982:

was there not a post about this already.. that I already answered?

7900xtx has been tested at pcie 1 - 5 (all x16)

it had the same performance pcie 3 - 5
but at pcie2.. it lost about 3% performane at 1080p and 1440.. and 2% at 4k.

since pcie 2.0x16 is exactly the same bandwith as pcie 3.0 x8.. they likely will function the same all other things the same.

so yes running an 7900xtx at pci3.0 x8 will likely cost you 2-3% performance
when compared to pcie 3.0 x16

but the chance your cpu is costing you far more performance loss due it bottlenecking such a gpu is considerably higher
(what cpu are you using that still used pcie 3.0)

Intel i9-10850k 10 cores 20 threads OC 5.1 Ghz all core

presuming you run that 7900xtx 4k.. without overclock that be a hefty 12% bottleneck.
but as you overclocked it 3.6 -> 5.1 ghz.. your likely ok in that front.

[Brimac]

Can afford 7900xtx +1000watt psu but cant afford 80-40 dollar new case. buy new case problem solved

[gwwak]

Get a new case? A $50 can solve your issues if you look carefully.

[Teammates go mid 2% slower]

So the 7900xtx isn't coming. It turns out that the chinese seller on amazon 'Hoyee' has been scamming people by sending them lockets instead of gpus. Thankfully I got my refund from Amazon. The thread is here:
https://www.reddit.com/r/buildapc/comments/1ike1xj/9800x3d_from_amazon_seller_hoyee/?sort=new