Re: SRBMiner Cryptonight AMD GPU Miner V1.6.8 - V8 & algo switching
1.6.8 hashrates is lower for me 
cards (both sapphire nitro+ 4gb) / hashrate 1.6.7 / hashrate 1.6.8
rx470 / 740 / 720
rx570 / 760 / 740
algo: bittubev2
i switch back to 1.6.7
cards (both sapphire nitro+ 4gb) / hashrate 1.6.7 / hashrate 1.6.8
rx470 / 740 / 720
rx570 / 760 / 740
algo: bittubev2
i switch back to 1.6.7
You need set gpu by hand, not use auto. Auto value lower in 1.6.8