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I want to use an AMD Ryzen 2400g, but I will be using OpenCL on three discrete AMD Radeon RX580s installed in it. Will the Vega compute units on the APU still be available if I install the Radeons? Or does their installation disable the integrated vega GPU?

Thomas Browne
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  • I did some research, look like [NO](https://community.amd.com/thread/225669). You'd have to disable iGPU in order to use dGPU. Also, the Ryzen APUs only have 8 PCIE lanes, eg. PCIE3 lanes split x8/x0 instead of x8/x8 (see detail pane of [spec](https://www.msi.com/Motherboard/X370-KRAIT-GAMING/Specification)). You'd need adapter to fit extra dGPU. – guest Apr 05 '18 at 19:44
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    I know that for Intel the integrated graphics is still available (and people commonly mistake which port to plug monitors into) so I would expect AMD's Ryzen to behave similarly. If it is available, it will still be software-dependent (ex: I know that Linux doesn't like using integrated and discrete graphics simultaneously). – Aaron Franke Apr 06 '18 at 06:42
  • It won't be "disabled" but what do you want it to be available for? – HackSlash Apr 06 '18 at 20:08
  • @HackSlash Do you have any proof for that? I searched in various hardware forums and there is no report of both iGPU & dGPU enabled for Ryzen APUs. CMIIW. – guest Apr 07 '18 at 13:02
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    I want to use both the integrated GPU and the discrete GPU for compute via OpenCL – Thomas Browne Apr 09 '18 at 13:23
  • @guest I've found that you can't crossfire with them but nothing about it being disabled. The only evidence that suggests it is available is that DX12 multi-GPU is supposed to be able to access it. I guess someone has to test it. – HackSlash Apr 09 '18 at 15:36

2 Answers2

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As of now, Ryzen APUs won't coexist with GTX1080Ti[1], GTX1050[2], GTX1050Ti[3], RX580[4][5] and Vega 56[6].

Even if it is fixed with updates from AMD, Ryzen APU only has 8 PCIE3 lanes for dGPU[7], eg. PCIE3 lanes are split x8/x0 instead of x8/x8 (see detail pane of spec). You'd need an adapter to fit extra dGPUs, as per your intent to run 3 dGPUs in 1 rig.

guest
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  • That's a cool reference/resource/citation type thing you did there with that answer keeping it clean with all the references. Wassup, or `` with it!! LOL – Vomit IT - Chunky Mess Style Apr 11 '18 at 20:39
  • Okay but, what if only install 1 discrete GPU. Will I be able to use the dgpu AND the vega APU at the same time? So put another way, I hear you that 8 lanes i not much, but any of the GPUs you mentioned work fine with 8 lanes as a single card. Can I use the vega APU *and* the dgpu at the same time? Is there a restriction on what that dgu should be if I only install *one* ? – Thomas Browne Apr 19 '18 at 20:27
  • All the links I quoted indicate incompatibility when using Ryzen Vega iGPU and dGPU simultaneously. If you have read the links there should be no doubt. You can't have both. Nowhere did I said x8 PCIE lane would limit the performance of the dGPU. It is rather the hardware/driver limitation that you can't run both iGPU and dGPU at the same time for Ryzen APUs. – guest Apr 19 '18 at 22:12
  • @ThomasBrowne Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/74787/). – guest Apr 21 '18 at 00:48
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to say these response are BS is an understatement Ryzen 2200/2400 ave available pci-e 3.0 x8 link speed available that can be used for external graphics (if one so chooses) it is not easy to do so by all means, but claiming it is not possible is not at all truthful.

AMD made sure there was a limit so you could basically only pair up with 1 GPU so potential miners would not even bother using as such.

Ryzen 2200/2400g with a x8 link speed is basically enough bandwidth leftover to feed any current single gpu from AMD or Nvidia up to about Titan V or possibly some dual gpu on 1 card configurations.....they really should have given the ability to disable the Vega graphics core to shift between the iGP and dGPU as needed, maybe this will come with BIOS updates, however, like I said and I have been spending quite a few hours researching this for my own information, you ABSOLUTELY can pair up Ryzen 2200/2400G with a discrete graphics card.

there is a limit of 1 gpu however, so if your plan was to use it for mining, likely the cost would just not be worth the attempt, better off to get something like a Ryzen 1200 and a full size x370 or something like that (more pci-e slots)

anyways ^.^

Maurice Fortin
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    if only this answer had come before I was forced to award the bounty. In other words, what you are saying is, I can install for example an Nvidia 1050ti, which in no way will exhaust 8 lanes, and still use both the onboard vega graphics AND the nvidia card, right? I am not wanting to do mining but I do want to run both OpenCL (on the vega APU) and CUDA (on the discrete 1050TI) simultaneously... – Thomas Browne Apr 18 '18 at 14:49