sounds like you better go back to factory stock to me ?    slot 75w   6 pin 75w  8 pin 150w   that's 300w  ???   that's pretty good risk to use a 3ed party bios mod  anyway and all your own risk if it fails to work out   or damages your card in some way  ?
 
http://forums.evga.com/Where-i-can-find-a-modded-bios-of-8400410090-of-a-980ti-Hybrid-m2540681.aspx
 
 
 
my hybrid stock out of the box ? [22c idle-48c max I ever got it ]
http://imgur.com/BLA7QfW

it will peak it still    not that I recommend anything  is with my hybrid   I use precision x   and used its voltage thing  and up it I think to 18%  ?  and bumped my  stock voltage from like 1.193 to 1.212 and that wen a long way just in doing that   like in gpu-z where you see the  orange  pef reason   spike  in the blue field was more under control  and for the most part gone nothing but blue     I don't just  run precision x  full time and only what I need / want  to   cause its not needed for most everyday things  or games    but try that ..  and set the slider to 110%   with out adjusting any clocks   cause to should boost to match the extra voltage you adjusted it to  .. 
 
my card has peaked to 278w   so it can bang it  this is showen in hwinfo 64 ..under gpu power I think if your system supports that reading
 
I think you may find your older sandy platform may come in to play as well on these newer cards  [opinion]
 
 
running valley and gpu-z render test at the same time 
http://imgur.com/CpI1F2t
 
you take like this card   to me that's not good   way too much orange  in that blue field  ??  things need to be backed off a bit  or that cards voltage is too low for the clocking   1.187 aint holding up to that overclock   [more opinion]
 
http://imgur.com/YDTq3pV

well yes and no .    your card is asking for more power    so  say at stock your card is like mine at 1.193v   that  indicator in gpu-z will show orange spike  at say 96% draw  but it will or maybe a slight thin 1/2 way up the blue field  line  and the higher the draw you get to the 110%  the thicker and taller that line gets   so  when you increase that voltage to  1.212 that allow more head room before you peak that 110% out  thing is whats safe pre card ?/   the more you add the more its going to take until it fails .   its all about finding the proper balance and full stability of each and every card   some take it well some just ok some may not at all  [ luck of the draw]
 
I ran heaven and to show you the peak watts this card drawed  for a example for above  [256w] 
http://imgur.com/N4V6t5Q
 
but voltage is a different animal  and the more important.     you can see the watts are limited from here according to this info on the bios's .
 
Board power limit
  Target: 250.0 W
  Limit: 275.0 W
 
https://www.techpowerup.com/vgabios/179138/evga-gtx980ti-6144-151104
 
I feel its best to leave that alone   what to worry about is whats the safe max voltage  to run any overclock you put to it for 100% all day running everything stable  ? all that's back to t your own risk and how well your card can take any voltage with out issue ??
 
to me where you worry about the watt limit is in your amps of your psu ?   so the card  may peak to that 275w that's  that's 23 amps  drawing off your 12+  just for the card alone 
 your 650w psu should  hold  54amps at the 12v+   and leave you with 31 amps for anything else in your system   so you should be well covered there  in the watts dept..

ok, sounds like your back on track  ?    just remember a good overclock is not a 5 min job  and a lot can depend on your card in how it takes any  ..
 
I don't do bios mod's so I aint much help on that part anyway   unless its a old out of warrantee  or cheap-o card  if something went bad wrong I was going to replace it anyway 
 
[in reference to that wording in blue from that link you gave  on that bios mod ? ]  
http://www.jonnyguru.com/forums/archive/index.php/t-7212.html
 
good luck 

well I got to get ready for football   so i'll check back   when I can