[NAME] not sure where you are getting your information from. 12v 18 amps is a limit and its set for UL94v certified power supplies. This is based on the wire gage as well as the max amperage for the connector pins. UL rated supplies will not burn a wire because over current limit crowbar will shut the psu off if that happens too many times the input AC fuse will blow and its not a user replaceable part. There is death inside a power supply with voltages exceeding 400V able to kill you by stopping your heart even after unplugging from the wall. Note the clear limits for a 12v only XPS 8940 power supply. This standard applies to many things not just Dell power supplies. [URL] Slot power rating is PER SLOT so with 4 slots thats 4x the power for the table below. 5.5A + 2.1A + .5A + .5A = 8.6 amps 12V and 12 amps 3.3v this is where the 142W bare minimum combined power needed for 3.3v/5v rails is involved.  SFF rates this rail set at 90W max. This is also why only MT supports 75W GPU. X4 wired slots are 25W max meaning the Black slot in some models is 25W max. The BLUE Primary Slot supports 75W only in the MINI TOWER. Note in DT it says 50W max. [IMAGE]X4 slots are 25W max [IMAGE]Note 3.3v and 12v involved PER SLOT   [IMAGE]XPS 8940 power supply.
Ok, so I'm wondering how many watts a PCI-E slot can draw. Let's say you have a PCI-E card of some sort and it's plugged into the PCI-E slot. The PSU wattage doesn't matter right now, just imagine it's 1600 watts I guess. How many watts could that PCI-E card draw before the PCI-E slot breaks or something? PC specs if you need them: Stock Optiplex 790 SFF case i5 2400 Intel HD 2000 (Integrated graphics) 8GB ram 2000 GB hard drive D28yy motherboard 240-watt gold power supply (stock) Windows 10 Pro edition
What's the maximum wattage a PCI-E slot can handle on a dell Optiplex 790 SFF?