I hate removing it too :P
Temps can make ALL the difference in the world, even just a few degrees guys. Your temps are very high.
After I found that the 355+ drivers can cause many problems when overclocking and I read thru your thread yesterday, I started looking for other things as well and spent some time on this for two days:
I tested two pieces 73% asic all day. One piece was crashing the driver over 1500 similar to yours first time I tested. When I see a card doing this I know something is not right instantly because about all KPTi can clock over 1500. The range is around 1520-1570 on Max overclocks on air:
1. Max OC depends on ASIC and room temps for sure. Maxwell is already at teh thermal limits even on just stock boost clock. For the card to perform well and to OC all the way on stock cooler that its capable of, it needs about of 26-27c ambient room/case temperature. If the surrounding air of the card is much hotter than this, the max air OC will lower.
2. For now DO NOT use 355+ drivers as they cause grey screens and driver display errors. Try 353.62 first if having issues. Uninstall the old driver and use driver sweeper to remove all NV entries in registry. Reboot.
3. Put the bios back to the first position (normal) and reflash the card to 5998V360.rom which is the factory shipped stock bios(since this is stock nv green light bios, no need for crack flash)
4. After flashing bios, boot into windows and install 353.62 drivers and test the card again starting at 1500 with fan speed 100% (approx 2700rpm on default bios)
Let me know what happens and also take a picture of the benchmark running with precision osd enabled so I can see loaded temperature during 3dmark game test. If you have to use an open case then do it. Your system MUST have proper airflow for these cards to run at max.
This is the bios posted at KPC which I want you to flash to:
http://xdevs.com/evga/980ti/5998V360.rom
 
BTW...After I did all this to that 73% asic card that was stuck below 1490, it can now run firestrike 1540mhz, I can loop the 3dmark demo at 1525mhz and Heaven about 1525mhz as well :)
This is a great card! but its stuck 1490 previously. Follow the steps I laid out EXACTLY, see if it helps you.
After you follow the steps, try the first OC test with no overclock on memory, then try again with +598 offset which give 4104mhz. Somec ards will clock higher on core when you OC the memory too.
 
 
Did you try this ^^^^^ ?


353.62 has been the best for me, both for gaming and OC'ing. 355.82 was pretty stable in games but gave me lots of issue's when benching and lower clock's as well.
 
Have you tried OC'ing each card individually to find there max OC when not in SLI ?  My two kpe's are about 20MHz apart from each other on the core and 50MHz on the memory. One card is 75% ASIC and the other is 75.1% ASIC.