I'm hoping I can get some clarity on an issue I encountered last night with my older desktop and new power supply. I am gathering parts for my first new build and picked up the new PS last night. To test out the new fun lights I decided to pop it into my older desktop listed above. After opening the case and getting everything unplugged I double-checked with my old PS the components that needed to be plugged in and everything worked fine and the computer booted like normal to the login screen.
When I plugged in the new PS to the same components, all of the fans would run on the case, processor, and video card, but my monitors wouldn't recognize any input coming from the tower and would go to power saving mode. I triple checked all of the cables by unplugging and plugging in again with similar results.
Upon aborting this idea I reinstalled the old PS and am currently experiencing the same symptoms as when I tried the new PS! Does this sound like a fried mobo or am I missing something here?
One thing I did not is that with my older power supply I needed to plug in to 2 different power places on the mobo (the 20+4pin and another 2x2 connector (sorry don't know terms)). However on the new PS it did not have a 2x2 cord (just a 3x2 plus a 1x2 similar to how the 20+4 cables come) so I just used the 20+4 when I booted. Would that have done anything negative to it?
Any insight you can give me either diagnosing or ruling out any potential issues would be very helpful.
I should clarify, my desire is to get the old PS working in the computer again so that I may donate it to my parent's house and take the new PS for my new build so getting the new PS to work in the old comp is out of my scope.