If the voltages are reading as you say then you should dump the bios using GPU-Z and then use Hawaii reader to make sure that the voltages haven't been hard wired. In the card's BIOS each DPM state should rely on a lookup table which sets the voltage for a given state based on the asic quality of the card (I believe). Therefore the default voltages are different for each card, apart from state 0 which is always 968mv I think (wattman doesn't let you change that).
For instance, here is my card which is running quite undervolted (-88mv under stock):
You can see in the GPU Freq table how my voltages go 65282, 65283, 65284, 68285 then 1150, 1156, 1162. The last three are not stock voltages, those are set by me and duplicated onto the limits tab as well. So make sure yours run up like the 65282 etc to make sure you have a stock bios first of all (those 65k numbers aren't voltages, they tell the card to use the lookup table for its voltages).
Secondly, regarding black screen on 290s etc, I think those issues were mostly due to voltage too low. My card did that at idle when I undervolted using MSI AB because I think it was applying the undervolt to all the states or something odd.
Edit: Oh I should add, if you do change voltages in your cards bios you MUST have uninstalled afterburner and drivers first, otherwise if those tools apply an overvolt on top of any changes that could cause issues so always DDU your drivers -> flash bios -> reinstall drivers if you need to go down this route.
Edit2: To answer your exact question also my voltages are:
S1: 1031
S2: 1037
S3: 1075
S4: 1118
S5: 1150 (hardwired)
S6: 1156 (hardwired)
S7: 1162 (hardwired) (1237 stock +13mv manufacturer offset = 1250mv)
Card is an MSI 290x gaming.