So your +12V still shows a drop to +7.5V when running Furmark, BUT NOT with prime 95??
Are you still getting the Lock-ups/crashes/freezes??
First I don’t think that the 7.5 V on your +12V rail is valid unless it is a voltage spike that is faster than your PSU can react to. 7.5V > xx microseconds should shut down the system. More likely the 7.5V value is a Rail Limit imposed by the software, that is any reading below a set point are all displayed as a set value (your case 7.5) example the software expects the +12V to be between say 10.5 v and 13.5 V. If it detected a value of say 10.4V it would not display 10.4, but display 7.5
Your initial PSU is listed as a very good PSU, better than the corsair CX series.
Since you are getting the same results with both PSU, I would tend to rule out the PSU.
This tends to point more toward the GPU (Not normally the culprit).
This is ONLY a guess, but what could be happing is that your GPU is momentarily causing a very low impedance to the +12V (ie a couple of microseconds), The PSU voltage is dropped, but before the system say SHUT down the Low impedance has returned to normal and the PSU rather than return to normal first overshoots the normal value ie jumps up to say 13.5 V then back to +12V. In extreme cases this can cause what is referred to as damping oscillations.
And herein lays the problem, you nor most local computer repair shops are equipped to measure this. Requires a dual trace O'scope, one trace for Voltage and a 2nd on for measuring current. Problem compounded it that a current measurement would require some special cables as compute PSU cables are not designed to allow this.
You, or the local shop are kind-of stuck with the Trial an error method of replacing components - Can be expensive as you already paid for a 2nd PSU to replace a quality PSU.
Then there is also a possibility that it is sensor related (Motherboard reporting) or software (reading what the MB is reporting. I tend to rule these two out as they in themselves should not cause the "freezes/crashes"
Sorry I'm not more helpful, Hard to say, but for grins and LOLs
1) Place O'scope voltage probe on Pin X
2) Short the +12V wires to one wire then expand back out to x number of wires to Pci-e pwr connector (this is for a current probe.
3) Set trigger to above nominal value, and slope to Positive
4) ect
O, My Dual trace scope cost list price is around 3 Grand.
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