I'm thinking about doing a CF. Now I have RX580 Nitro+ SE, but I'm looking for a 2nd card. Was thinking about 2nd Nitro+ SE or Nitro+, but they cost a little (have enough, but if I can spend more...) - 500 (Nitro) or 550 (SE) PLN for the cheapest ones (used ofc) - it is 120/135$.
Than I thought about RX480 with RX580 BIOS, but there I would need one with 100% working BIOS and Strix OC would be best coz of (I believe from what I read) best cooling capabilities of all RX480 cards. Found one, but seller already bricked two cards and is not willing to play with more.... (there I would pay ~400 PLN = ~100$).
Than I found, here on reddit, info that RX480/580 + RX470/570 would be practically same as two RX480/580. That gave me more field to look for cards. And I found "holy grail" - Nitro 8GB for 280 PLN (70$). Only problem it is mining one. Do You know id it will work with normal RX580? Present one would act as video out card, so I don't mind that it doesn't have any ports out. But... WILL IT WORK? AS Mining RX570 has clocks at 1420/2250 and Sapphire RX580 has 1430/2000, than there won't be a lot of difference (and RX570 will be 2nd card not the main one).
PS. Right now I would like to thank for all the "CF is dead", "sell it and buy newer GPU", etc. comments. I don't have time, money to do that, or don't mind, or give a f. Thanks, danke, merci, dziękować!
IF the RX 570 is a mining card where the BIOS has been modified I would first suggest to open a Sapphire Support ticket and see if they will send you the original BIOS for your GPU card. Probably would need to send them the Serial Number of the RX 570 to be sure it is the correct BIOS.
If Sapphire can't help you, you can download Sapphire RX 570 8 Gbyte BIOS from PowerTechUp website from here: VGA Bios Collection: Sapphire RX 570 8 GB | TechPowerUp
The website has a program you can use to update the GPU VGA BIOS.
By the way, When you receive the used RX 570 and have it installed and running, download a free program called GPU-Z and compare the specs to the original Sapphire RX 570. In case they sent you a fake RX 570.
I didn't order it yet.And it's not modified GPU, but one made with mining in mind, so there is no "normal" BIOS. At least not for that card, as I can flash BIOS from normal RX570 (one with outputs).
I already created the ticket, but asked about CF capabilities, no for the BIOS (will remember it for later).
I understand now what you meant by the GPU being a mining card. Many miner Users takes a regular GPU card and modify the BIOS for mining which is what I thought you were talking about.
If the main GPU is the RX580 and the RX570 is the secondary you can do it. Since you will be using the outputs to the RX580 and not the RX570.
I see you opened a Thread at Linuschip tech site. They say you can and answered your question: https://linustechtips.com/main/topic/1165700-crossfire-of-normal-rx580-and-mining-rx570/?tab=comment...
From AMD concerning Crossfire: https://www.amd.com/en/support/kb/faq/dh-018#faq-AMD-CrossFire%E2%84%A2-Overview
IF you find out the Mining Card BIOS doesn't work then you can try in install the Original RX570 BIOS and see if it works.
My build has all things You underlined, except I'm not sure about that last one.
1. Primary GPU has outputs, so secondary doesn't have to have them.
2. Both are RXes. Except they are not the same (580 and 570), but same graphic chip (Polaris 20).
3. Mobo (ASUS X570 TUF Gaming has two x16 PCIes (x16 and x4).
4. They are compatible.
Only dunno about Crossfire support in Mining BIOS...
Once you have the RX570 installed and running, see if Crossfire is showing in Radeon Settings.
Then you can decide what to do after that.
More than likely they will not work together properly as the mining cards are not optimized for gaming they are set for compute instructions. If they do however, realize they will only work at the lowest common denominator of speed. Meaning both will operate at the lower cards speed. I would only do crossfire if you only have a couple of games that you know crossfire is working on okay. Many games that did have it working at one time are now broken for crossfire. It honestly doesn't have good support anymore and I would highly recommend you spend you money toward a single card solution that meets your needs.
Regardless by official specs crossfire cards are supposed to be of the same model. like 2x RX580s. The RX 580 and 570 are both Polaris but their differences are more than just speed. Also before you go down this path be sure you have a power supply that can support both cards too. Just know that Crossfire is discontinued after DX11 (and currently has horrid support as does SLI) and Multi GPU is gaining no traction under DX12. So the best you can hope for at most is a handful of games that may work and may then be broken in an upcoming driver update or game patch. Not to be negative but it's just the reality of the situation.
In the end I managed to sell older mobo and had enough money for 2nd 580 Nito+ SE.
For a moment I thought about newer card, but seeing the prices off new cards with similar performance like one 580 (1650/1660/1660S or RX5500) I thought - hmm, for that I could buy 3 RX580. Nope, won't buy it.
And as some stated (not sure here or in anther places I asked or other people asked): It's true that AMD and Nvidia may be trying to end CF and SLI. However DX12 brought multiGPU support and I have faith in Microsoft (new thing for me) that it'll stay.