Power Usage and Final Thoughts
One of the other aspects you have to keep in mind when running multiple cards is just how much power they will draw. To test this I used 3DMark Fire Strike Performance Test to put the cards and our whole testbench under load then documented the peak wattage draw. The end result looks a little crazy when compared to all of the other dual card configurations at 555 watts. Even individually both RX580’s pulled a lot of power, so pairing them up together is just asking to spin that power meter faster. Sadly I don’t have any old power draw numbers to compare with here because I had to change our testing procedures. I actually had to change it specifically because of Crossfire and SLI testing though, Valley Benchmark that I used to use to put everything under load wasn’t really pushing Crossfire and especially SLI cards properly as the support was dropping. 3DMark is always supported though, that’s why I moved to that.
So would I go with two RX580s in Crossfire? Actually no, not this time around. I was actually really considering it for our Ryzen project build but what I found is that even when they perform really well and when there is support the performance at the higher resolutions the performance drop is very noticeable. So if I was looking to get the best possible performance at 1080p this would be fine, but a single RX580 already does more than enough at 1080p. It is when you are gaming at 4k or ultrawide resolutions that you really need the power and currently Nvidia's single card options like the GTX 1080 Ti or even some of the 11Gbps GTX 1080’s perform better in that usage. That’s even when complexly ignoring the fact that of all of the tests I ran we only saw a little over 50% of them even supported by Crossfire. SLI and Crossfire both have this issue though I wish AMD would at least publish a proper list of games supported like Nvidia does.
Now when looking at the pricing, two RX580’s paired up is going to run you from $460 to $600 depending on what model you go with. For comparison, GTX 1080’s start at $480 and the 11GBps models should be about $100 more. This is why AMD needs Vega asap, the RX580 is a great card but even when in Crossfire it doesn’t really offer the high-end solution that some people need.