I have both cards. The Sapphire Nitro+ RX 570 4GB is a good card. It overclocks well for a 570 and runs cool. It uses a bit more power than my other 570's which are Powercolor Red Dragon's. With a simple 'one click timing patch' using Polaris Bios Editor' v1.62 from jaschaknack and a 1200 MHz core clock and 2020 MHz on the memory, I get ~28.5 MH/s and 740 MH/s dual mining DCR.
The advantage of the RX 580's over the 570's is the 580's uses faster memory, 8,000 MHz for the RX 580 vs 7,000 MHz for the RX 570, which can overclock higher. The RX 580's have better dual mining performance as well. The MSI Gaming X RX 580 8GB is a good card, but I like the Sapphire Nitro+ RX 580's better. They Sapphire Nitro+ RX 580's run cooler than the MSI Gaming X RX 580 and I can overclock the memory to 2200-2250 MHz on the Sapphire vs 2100-2120 on the MSI. With the MSI I get 29.5 MH/s on ETH and 860 MH/s DCR dual mining.
My brain hurts even more lol
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
The Sapphire Nitro+ RX 580 was an option but its out of my budget (another £50 per card).
It has to be one of the two above. Remember, I can get
5x Sapphire Nitro+ RX570 or
4x MSI RX580. Unless the 8GB on the RX580 is going to be advantagous in the future, my heart is pushing to The Sapphire.
Is the 8GB really going to help in the next one/two years? Its if and butts.
Sigh..