RE: 35W Limit on PCIe x16 slot: Optiplex 790 SFF
Thanks for the reply SammyVV. I wasn't concerned about the so-called wattage limitation of the PCIex16 slot. There is no such disclaimer on my motherboard or any of the manuals. Therefore I am only concerned with the current demand on the +12V rail and the heat produced. (The PSU's +12V rail is rated for 17A)
I estimated the amps (yes, I meant amps) by taking an amp reading with my Kill-A-Watt meter set for current. It read 1.4 amps at its max on the primaru side of the PSU. Since the PSU's transformer is a 10:1 step-down ratio (120V primary/12V secondary), I estimated the total secondary amperage at ~14 amps not counting power factor loss*. Since the +12V rail is responsible for nearly all of that amp draw, I assumed the most it could be drawing was 14A or so.
I ran the Firestrike benchmark and got a score of 3847 (I5-2400 and GTX 750 Ti). Max current draw was an estimated 12.4A
* Since I'm taking my reading on the primary side of the PSU, power factor would be in my favor. I.e. the secondary side isn't using all that power. Some is loss to heat, and capacitve and inductive reactance.