My Sapphire non-oc came with 1.21 stock voltage, so you can easily crank it up to that.
On a different note, I could really use some feedback on this heaven score; its way too low for 1200/5500 as far as i can tell. Using Trixx, board power limit at +20, 2500k at 4.0.
Interesting! Could you post a GPUz screenshot of default voltage?