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GPU through chipset

pompi

Did anyone ever try to run a gpu over a slot connected to the chipset?

The idee is to keep a workhorse gpu connected with 3.0@16x and a lower end gpu for simple desktop use over chipset with 3.0@4x.

The alternatives are:

- run both with 3.0@8x

- buy a x500 board

 

currently I'm running a c7h with x470 chip. I try to update my gpu to a rtx3000 or rx6000. Thus I don't really want to run the gpu at pci3.0@8x.

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Not worth the effort. Plus you need a CPU that has a GPU (Ryzen APU / 3400g for example)

If you don't use the main gpu, it will still sucking power when idle which not a whole lot difference if you do simple task with it.

Ryzen 5700g @ 4.4ghz all cores | Asrock B550M Steel Legend | 3060 | 2x 16gb Micron E 2666 @ 4200mhz cl16 | 500gb WD SN750 | 12 TB HDD | Deepcool Gammax 400 w/ 2 delta 4000rpm push pull | Antec Neo Eco Zen 500w

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20 minutes ago, pompi said:

Did anyone ever try to run a gpu over a slot connected to the chipset?

The idee is to keep a workhorse gpu connected with 3.0@16x and a lower end gpu for simple desktop use over chipset with 3.0@4x.

The alternatives are:

- run both with 3.0@8x

- buy a x500 board

 

currently I'm running a c7h with x470 chip. I try to update my gpu to a rtx3000 or rx6000. Thus I don't really want to run the gpu at pci3.0@8x.

I dont get what you are trying to achieve... 

 

So If I got this right you already have an old GPU on your primary x16 slot?  and want to buy a new gen GPU (good luck with that btw 😛 )  and plug it in a different pci slot? 

 

Do it. 

 

What is the issue? 

 

an x8 lane will be perfectly fine for your GPU even if it is PCIe 3.0

 

but if you insist you can connect your older GPU to a x1 slot or a x4 slot no issue but I dont understand why you want to do such a thing... 

 

just use your main new gen GPU and sell the old one now that prices even for old GPUs are high AF you wont get any performance advantage if you keep your old GPU if anything you're running the risk of adding complexity/driver/compatibility issues by keeping it... 

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40 minutes ago, papajo said:

I dont get what you are trying to achieve... 

Just as I described. One gpu for heavy lifting. E.g. passed through to a vm. If you pass through one gpu you need another one for the host.

pcie3.0@8x actually seems to be to slow for the new gpu's.

 

Quote

What is the issue? 

I don't know. I just asked for experience. I know that it is far from optimal to run a gpu over chipset. Just want to know, if it actually works. There might be technical issues which prevent this from working.

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1 minute ago, pompi said:

Just as I described. One gpu for heavy lifting. E.g. passed through to a vm. If you pass through one gpu you need another one for the host.

pcie3.0@8x actually seems to be to slow for the new gpu's.

 

I don't know. I just asked for experience. I know that it is far from optimal to run a gpu over chipset. Just want to know, if it actually works. There might be technical issues which prevent this from working.

Firtst of all your mobo is an AM4 one thus it will have PCIe 4.0 so no issue at all even if you are skeptical about how it would fair on a PCIe 3.0 x8 (a PCIe 4.0 x8 is much faster) 

 

as for the PCIe 3 x8  the difference is negligible 

 

https://www.techspot.com/review/2104-pcie4-vs-pcie3-gpu-performance/

 

Especially if you want to pass it through a VM where the overhead for that will be greater rendering the available bandwidth of a PCIe 3.0 x8 totally fine. 

 

Having said that as mentioned before you totally could just plug your new gen GPU on the x16 slot and have the slower one at any other slot which will be ok as well especially if you do not want to game on the older one. 

 

 

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5 minutes ago, papajo said:

Firtst of all your mobo is an AM4 one thus it will have PCIe 4.0 so no issue at all even if you are skeptical about how it would fair on a PCIe 3.0 x8 (a PCIe 4.0 x8 is much faster) 

Only x500 and b500 upwards support pcie4.0. It has nothing to do with am4.

As mentioned I'm using c7h with x470 chip -> pcie 3.0

I appreciate that you try to help, but please check the infos I provided and don't ignore them =(

 

I think the difference of pcie3.0x8 vs pcie3.0x16 is quite noticeable in some cases. This wasn't the case with last gen gpus. 

 

 

On the prime x570p it seems like dual gpu is actually intended to use the chipset on the 2nd gpu. But that's x570 and a different story.

https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/PRIME_X570-P/E17441_PRIME_X570-P_UM_v3_WEB.pdf

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5 minutes ago, pompi said:

Only x500 and b500 upwards support pcie4.0. It has nothing to do with am4.

AMD has backwards compatibility for x470 and b450 chipsets to run PCIe 4.0 which one do you have? 

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4 minutes ago, pompi said:

yb6mlwumy4931.jpg

 

You should be able to check GEN 4 then on the advanced tab 

if not then update your bios (EDIT: I think youll have to have atleast a ryzen 3000 series CPU though but I am not sure about that) 

 

But as I said before there is no practical issue you can run your main GPU on x16 which either 3.0 or 4.0 is more than enough

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Interesting. I can't verify that, because I do not own a 3000/5000 series cpu yet. Still rocking 2700x.

 

Quote

But as I said before there is no practical issue you can run your main GPU on x16 which either 3.0 or 4.0 is more than enough

yes that would be enough.

My issue is that the speed of slot1 drops to 8x if I put something in the 2nd pcie slot or the upper m.2 slot.

I don't want that.

If pcie4.0 actually works on the c7h, does it run pcie4.0x16 with single gpu and pcie4.0x8 on both slots

 with dual gpu?

image.png.c32fa872bb0013056db119395328d70c.png

 

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4 minutes ago, pompi said:

Interesting. I can't verify that, because I do not own a 3000/5000 series cpu yet. Still rocking 2700x.

 

yes that would be enough.

My issue is that the speed of slot1 drops to 8x if I put something in the 2nd pcie slot or the upper m.2 slot.

I don't want that.

If pcie4.0 actually works on the c7h, does it run pcie4.0x16 with single gpu and pcie4.0x8 on both slots

 with dual gpu?

image.png.c32fa872bb0013056db119395328d70c.png

 

Yes it would run PCI  4 x8 with both there is really no practical reason to headaches about that. 

 

 

 

 

 

and so on and so forth... (notice that top of the line GPUs are used here so slower ones will have an even smaller difference) 

 

Other things (such as CPU type/speed) will affect your framerate much more so dont even bother lol 😛

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3 minutes ago, papajo said:

Yes it would run PCI  4 x8 with both there is really no practical reason to headaches about that. 

no reason? There is not a single source that confirms, that this works.

 

There is only that one bios screenshot. This just shows the bios options, which is not even fully visible.

And there is this table from asus(?) which indicates that pcie4.0 only works on 1 m.2 slot and nowhere else:

image.png.49cb9767c7fd8c72795bbdb2ddfb8827.png

 

That's a lot of headache in my opinion 😞

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Not even sure if pcie 4.0 on x470 is still a thing. It seems that AMD was against it and it got removed again.

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To put it under a technical perspective. 

 

 

Suppose you want to push a 4K 8bit signal @ 300 FPS

 

 

each subpixel (red green and blue which consist a pixel and you will have 3840*2160 of them on a 4K monitor)contains 1 bit of information. 

 

So we have 3840 * 2160 * 3 * 8 *300 = 59719680000 bits per second or in other words 59.72 Gbits per second. PCIe 3.0 x8 has about 63Gbits bandwidth .... 

 

So even if you could play a game at 300FPS on a 4K monitor (which would be higly unlikely even for a 3090 especially paired with a ryzen 2700.... ) you still have enough bandwidth to do that. 

 

 

 

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What does this have to do with anyting? You just calculated the bandwith my display port cable needs.

 

Initial question was: "Can I run a gpu over chipset to preserve 3.0x16 speed on pcie slot 1."

 

 

pcie4.0 spawned the subqustion if pcie4.0 on x470 is a possibility. It's not! It got removed again:

https://hardwaresfera.com/en/noticias/hardware/asus-las-nuevas-bios-ya-no-soportan-pcie-4-0-en-las-placas-base-de-chipset-anterior-al-amd-x570/

 

Seems like it would never have worked in the first place on c7h:

image.png.7c0dda6502d88fac3a66136ac17b3032.png

 

I'm not interested in comparisons of pcie4.0x16 vs pcie4.0x8 vs pcie3.0x16 or how many bits my gpu pushes to the monitor.

It's not relevant at all.

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6 minutes ago, pompi said:

no reason? There is not a single source that confirms, that this works.

 

There is only that one bios screenshot. This just shows the bios options, which is not even fully visible.

And there is this table from asus(?) which indicates that pcie4.0 only works on 1 m.2 slot and nowhere else:

image.png.49cb9767c7fd8c72795bbdb2ddfb8827.png

 

That's a lot of headache in my opinion 😞

That may be outdated dunno I personally have a x570 hence I didnt bother to look deep into this but here is a reddit post that I found previously that confirms it is compatible 

 

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4 minutes ago, pompi said:

What does this have to do with anyting? You just calculated the bandwith my display port cable needs.

 

This serves to prove to you that PCIe 3.0 x8 bandwidth is more than enough for your needs and should not worry about it. 

 

All those +- 3FPS or so are just variation differences and statistical error margins not related to the pci 3.0 x8 lanes not being able to push that extra couple of frames compared to the PCIe 4.0 test.. in fact in the videos I included above you can see that with an intel CPU the FPS (hence the bandwidth) with PCIe 3 increased compared to the PCIe4 but with a "slower" (in gaming) ryzen 3000 CPU... 

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