Intend to be running dual/tri-fire 7970 Lightnings in the future with very heavy overclocks, they can pull quite a lot of power when heading north of 1.35/1.7v @ 1300+/1800+. Not to mention a (hopefully) healthy OC on the CPU. Also commonly the price difference between the 850 - 1200w units tends to be quite small.
Had a good look at the PSU, I'll try sort some pics but they really don't show anything, can't see any blatant leaking, bulging, rusted caps. But saying that I can only visibly see two large caps and around 5-6 smaller ones, think there are many more hiding under the heatsink.
Might even treat my self to a beer tomorrow if the PSU is dead!