Hey guys, its a bit early for build questions but im curious as to the whole unlocking 6950 -> 6970 deal.
Would this cause any sort of issues due to the limitations on part of the PSU and lack of cooling?
Im a bit weary of shortening its life span by running it too hot or overclocking it without the proper PSU.
Lack of cooling? You're getting the 2GB Twin Frzr, right?
Anyway, don't worry about the PSU. The +12V rail holds more importance than sheer wattage, and that Seasonic has a whopping 40A...it should power your unlocked card just fine.
Your issue will be more about the shaders and overclock. It's possible that you'll really get a crippled 6970, and have no worries.
It's also possible that you'll get a proc that didn't pass all tests (or was from a wafer where another proc didn't pass all tests) and was demoted to 6950 specs with extreme prejudice. If you do get one of these lesser procs, unlocking and overclocking may introduce instability and/or artifacting...if this happens, start by clocking down, which usually resolves that bad stuff while still giving you the extra pipes for a slight perf boost.
Another issue is the memory clock...or more precisely, the memory itself. For example, years ago I had a vanilla 6800 NV40, and was able to unlock the extra pipes and vertex shader (same as the 6800GT). To get near-6800GT performance, I also needed to overclock the memory, but alas, the vendor used lower-performing memory, and I was forced to clock down the memory back to stock (otherwise random, unrecoverable system hangs occurred multiple times a day). I still got huge improvements by unlocking, but not as close to 6800GT perf as I had hoped because I couldn't overclock the memory with any kind of stability.
If MSI is using the exact same memory on the 6950 as they do with the 6970, you should be fine, tho.