Best setting for 295x2

295x2 owners,

What's your recommended clock for max hash without tripping the core throttling temp?

Currently hashing 28.8MH/s per GPU using Claymore 7.3 ETH-only, Win 7 x64, stock BIOS, driver 16.10.1, stock clocks.

I found out today that the card starts to throttle core clock above 74C. I thought I'd to undervolt the cores, but voltage control is locked in TriXX/AfterBurner and not available in Radeon Settings OverDrive. Watttool is for RX cards only.

How do you undervolt this freaking beast?

Finally, should I be thinking about custom BIOS?

Please share your experiences/advice.

Thanks!