Tried reading through it but its nearly 200 pages long and just wondering if someone had an easy answer.
I know a CX500 Corsair will run 1 antminer s3
will a CX750 run 2 antminer s3
When you what to know how much load you can connect to a PSU, just go to its specification and look for +12V single rail.
Take out the amperage rating on that +12V rail and multiply it to amperage will give you the maximum you can load.
On a safer side to run 24hr, every day, do not full load the +12V rail. Keep a limit of 80% as a good practice.
There will be some current overload than the specified from any load.
Especially in case of Antminer S3 I doubt there is some more load sometimes than the rated like the hashrate jumping over and below specified 441Ghs.
So, always set 125% as load when doing sizing. For example the Antminer S3 is specified as 366W but you do sizing for 366*1.25 = 457.5 to be in a very safe zone.
Coming to the matter, CX500 the +12V is rated at 38A, that is a maximum of 456W can be loaded in idle conditions.
So one S3 can be loaded at maximum were we did out math and found 457.5 as S3 power consumption.
In case of CX750, CORSAIR website says its 12V @ 62A. So, 12*62 = 744W.
744/2 = 372W. So in idle conditions 2 Antminer S3-es of 366W can be connected to this power supply unit.
But as per our safety calculations we need 457.5*2 = 915W or ~ 76A required in +12V rail.
Now rest depends on you to whether load two S3s in CX750 even though its possible.
You have other PSU model options to safely run for a small amount of additional money.
Power Supply Units will not go worthless like Mining hardware.