In brief: With the crypto mining craze settling, listings of used graphics cards have started to flood second-hand product resellers. Pricing of these tends to be more attractive than buying the same graphics card new, but according to Taiwanese-based hardware maker Palit, the risk of getting a damaged graphics card is not worth it.
With Ethereum hovering around $2,300 per token and difficulty back to more than 7.0P, crypto-currency mining isn't as profitable as it was earlier this year. Mineable crypto alternatives are not much better than Ethereum, leading miners to sell some of their cards to recoup costs.
Most listings originate from the Chinese government crackdown on miners, but a quick look at eBay also shows that there's also a decent amount of used graphics cards listed. Some of them may not have been used for mining, but it's hard to know which ones were and the ones that weren't. Vague and empty product descriptions also don't help.
Most of these listings come with competitive prices, selling them below what we usually see at retailers (but not MSRP), but because they were used for mining, there's some possible loss of performance. At least that's what Palit says, claiming that independent tests have proven that after a year of use, the GPU's performance is reduced by about 10%.
That loss of performance doesn't always happen. If a miner is careful to ensure that enough air was reaching the card and the card was undervolted, the loss of performance may not be noticeable. On the other hand, some miners simply plug them in cranked spaces and start mining, making them work at higher than recommended temperatures, leading to possible oxidation of the soldered joints and faster deterioration of the thermal pads and paste.
Moreover, used mining graphics cards may also have been modified. Miners may replace cooling systems, thermocouples and fans to max out mining output, voiding the graphics cards' warranty and leaving the future customer unprotected if an issue arises.
As a GPU manufacturer, Palit doesn't get any revenue from users buying graphics cards from other users, so it's not surprising to see them trying to reroute buyers' attention to new cards. Nonetheless, they have a point to make on how careful you should be when buying a used GPU.