That's unlucky. I was probably extremely close to that happening but I got away with a screaming soon to be (October 2012) 9 year old PSU for 2-3 nights before landing the PSU I was chasing (this was in November when all parts were scarce).
Funnily enough, the old PSU was also a Corsair (750w HX+). Replaced with a BQ Straight Power 11 750w Plat.
Hope you can get up and running tomorrow. Have a blast with your new card.
Got the new HX850 Platinum in and....... all good!!
Running that first benchmark after installing it was a bit tense!
The old AX850 hasn't missed a beat before so am a bit sad to see it go, but hey ho at least I'm up and running.
I had to diagnose another weird issue in that if I have Displayport 1.4 enabled on my monitor and UEFI boot mode on my motherboard, I cannot get into the BIOS (PC locks up and no screen output, even if trying to enter BIOS via Windows settings). If I drop the monitor down to DP v1.2 OR set the BIOS to CSM boot mode its all fine. I googled it and is a very common thing by all accounts! Weird!