[NAME]  There is no such "proprietary 8 pin ATX" Standard  Using buzz words to associate connectors based on the number of pins or fitting into the socket is not helpful.  It is NOT ATX 12V , EPS 12V  or 8 PIN PCI-E Using those words confuses users into thinking that if it has a number of pins and fits its ok.  It ABSOLUTELY is NOT Ok. Connectors are keyed but impatient users can FORCE the wrong connector into the same 8 pin socket and DESTROY everything. CPU is Not GPU  [NAME]  [IMAGE][IMAGE] You need an EPS12v supply with an adapter or the Dell PSU that is PFC and 80 percent efficient. ATX is 70 percent efficient at best. 7VK45 365w, HuntkeyT1M43 365w, Delta Validated Dell cards with 365w power supply 36V90 Nvidia GeForce GTX 1060, 3GB, 120w DVP9W Nvidia GeForce GTX 1050 Ti,  4GB, 75w24K8H Nvidia GeForce GTX 1050,  2GB 75w 1MPR3 AMD R9-360 2GB, 75w   [IMAGE]Dell case can only use short cards [IMAGE]     [IMAGE]
After doing a atx case swap-out for an Optiplex 9020 MT i7-4776 but unable to boot it without it quickly shutting down, I learned the motherboard was defective, confirmed by a local computer repair shop I took it to that did a diagnostic, the cause of which remains uncertain. Square Trade was cool about comping me based on the coverage, & the repair shop is now looking for a budget intel gen 4 replacement Motherboard in the $100 range as a solution; however, with the cause of the defect unknown, they strongly advised against investing in a duplicate Dell Motherboard on my dime that could be bricked, based on the upgraded components I used for the swap-out, which otherwise all seem to be working.  So a new brand Motherboard was recommended, which will make my Optiplex a customized, unbranded PC. For anyone else here who has been in this unfortunate position with my particular model, what kind of Motherboard worked for you without any issues?      
Mandatory Motherboard Replacement For Optiplex 9020 MT i7-4776