Rendering in Cycles with defective GPU?

Hey everyone! I haven’t had any luck finding an answer to this question anywhere else, so I’m hoping someone here will be able to provide some insight.

I currently use a GTX 1080 for rendering my scenes. My friend has a completely identical card(same manufacturer and everything) but his has a problem that displays artifacting on his monitor. If I pair this card with my good one(the good one obviously being used for the display output) would the GPU cause any problems with the render?

I’ve played around with the idea of purchasing a second video card to speed up render times, but I don’t necessarily want to pay full price for a working one if I can get a slightly defective one for cheaper that can still handle renders fine.

I’d appreciate any input if anyone has any experience with this, thanks!

Your renders would probably also have artifacts