Thank you everybody for taking interest into my question
@aisle9 I also think that the RX cards are most probably legit, though they might have been used for mining or heavy gaming... Some of them also might be Chinese specific, like the "internet cafe" one or the 470D and 570D ones. On youtube there are quite a few reviews of such cards, for example by Tech YES City, Iskandar Souza (Portuguese) and a few Russians
@martward It's not like I would normally throw away $65 but then again, I won't get poorer if it turns out to be a bad decision I will certainly let you know if I decide to buy one of the cards, though the shipment might take up to a month...
@EL02 Yes, I might go with a more respectable seller, though they charge extra for basically the same thing... The same seller also has RX570 which has rather favorable reviews: https://www.aliexpress.com/item/4000380553288.html
@Sat1600 I'm from Poland. Ebay here is basically non-existent and on the local used market the same cards cost at least 35-50% more ?
Because of the strange cooling, currently I'm leaning more towards buying an RX 570, I'm not sure though if I should take:
RX 570 4GB for around $68
RX 580 4GB for around $88
RX 570 8GB for around $92
Which one would you suggest.
Also, in a bit of time, my brother will be upgrading his PC and then I could try and use his GTX 970. I know that Kodi will probably dump NVidia support in version 19 but for now it should be fine. Also VDPAU on GTX 970 supports less formats for hw decoding than VAAPI on RX 570 but possibly the I7 3770K might be able to software decode those (like HEVC 4K 10bit)?
Best regards and a Happy New Year!
Crocodil