Multiple GPUs Help
I'm going to be getting new graphics cards for a desktop gaming/general workstation/hash cracker by night, So I'd like to get something that is able to reasonably perform in all these areas. I'm currently eyeing either 2x GTX970 or a single GTX980Ti for my build, the budget for graphics is about US$600-700.

It seems to me from online benchmarks that for the gaming side, 2x 970s will perform similarly to a 980ti, so that part is alright.

Based on benchmarks that I've seen around the forums, it seems that a single 970 performs at about 75% of the 980ti, in terms of hash speed.

Since 2x970 is approximately the same price as a 980ti, would the 2x970 be the better option then? I also understand that the TDP of the 2x970 is only 30W more than the 980ti, so it seems pretty comparable.

Also, on a side note, would cudahashcat be able to use both gpus if SLI was turned on? Or would I have to keep switching between SLI on/off whenever I wanted to switch from gaming to cracking...
2x 970 would show the best performance. But yes, you would need to switch off SLI before using hashcat.
I've just been looking around the local second-hand sales forums, and I've found a few used 7970s at around US$140-150 each, would it now make more sense for me to get 4x7970 instead for the same total of around $600, since each one has a better hash/$ than the 970?

I'm a little worried about the amount of heat the 4 gpus will put out though, and whether anyone has experience trying to cool 4 of these cards in the same far I'm only able to source for 2 blower-style ones, the rest will have to end up being oem designs.
You will have issues with heat using oem 7970. Only go with reference design card! My advice better to go with 970 instead.

Best regards,
How about if I was able to watercool the other two cards that aren't reference? That would mean that the heat is being dissipated outside of the case?

I have seen a few times people mentioning not to use watercooling but I haven't been able to figure out why it would be worse than oem designs.

If I were to get the 970s instead I would still need to source for reference designs right? Those designs aren't as easily available here as opposed to the oem ones...
970 reference design card is a unicorn

epixoip suggested the following instead:


And as for watercool in my humble opinion will be complicated.

Best regards,
thanks for the help (: