I can't believe people are having trouble with msi cards and hynix memory! First of all, with the 4gb hynix cards use the 1500memstraps! Second, lower the gpu speed (1095-1191mhz range). Finally, start with a voltage offset of at least -14 in watttool. You should be able to set the mem to 1900mhz, but you may have to lower the p7 mem/gpu voltages even further. I'm getting 27/730 eth/dcr hashrate with 9.3 -dcri27 on a 4gb 470 msi gaming x. My msi ref 480's 4gb with hynix mem have the memclock at 2000 with everything else the same and the hashrate is ~28.6/800 eth/dcr. According to kill-a-watt all of the 480's use <100w for dual mining, and all the 470's <90w. I've got dozens of polaris cards and for me msi is the best for mining!
I agree, never seen a "bad" polaris card yet, samsung or hynix (480 or 470) are all doing 28MH fine.
However your power consumption numbers look way off. for me dual mine on voltages below 900mv is over 130W.
For example I've got here five card rig (2*480_msi_ref_8g & 1*470_Ntro+_4g & 2*470_ref_4g) doing ETH&DCR @ 140MH&3200MH pulling 795W from the wall.
PSU is gold rated thermaltake
By "all" of the 480's I meant the msi 4gb ref ones that I mentioned earlier, I use the 1750memstrap on the 8gb cards, and they do use more power but get a higher hashrate. Of course, clockspeed also has a impact on power consumption. The msi 470 4gb gaming x can handle mid to lower 800mV for the clock speeds I use. I don't have 470nitros but I do have 8gb 480Nitros and they required a lot of voltage tweaking since by default they have a +25mV offset if you check them with watttool.
I think many people have problems because of too high clockspeeds and too much voltage
