I had some good luck asking a question about my PC here a couple months ago, but unfortunately I'm back for round two.
I purchased a new PC from Dell ( http://www.dell.com/en-us/shop/dell-desktop-computers/inspiron-gaming-desktop/spd/inspiron-5675-gaming-desktop/ddcwrdsk920s/ but mine has a Ryzen 3 instead of the A10) to replace my HP that had it's PCI-E motherboard slot go bad on it. The HP was 5 going on 6 years old so I felt a new purchased was a good idea. I got a good deal on it, and it seems capable of suiting my needs.
After a brief setup period I moved my 4 TB drive from the HP to the new Dell. No problems. Then I tried to move my HP's power supply--a non-standard Corsair HX 650W Professional I installed myself--from it to the new Dell. After removing the Dell's PSU and making all the connections, I tried to start the computer. Nothing happened. No sounds, no lights, no smells, no nothing.
I tried different connections, including removing some extension cables inside, but it didn't work. I removed the Corsair and put the original Dell PSU back in. It worked perfectly. I put the Corsair back in the older HP. It worked perfectly. I put the Corsair back in the Dell. It doesn't work.
After racking my brain, I am at a loss. I don't get why it doesn't work. I've tried different power cables, and yes the switch on the PSU is on and it's always plugged into the wall outlet and PSU. The Corsair PSU just doesn't jive with the new system and I cannot determine why.
I'd like to note that the Corsair does not quite fit in the case. It did in the HP case, perfectly, but in the Dell case it's just a tad too big. I don't know if it not "locking" into place has any bearing on its functionality or not. The Corsair is also about 5-6 years old, but runs fine. I need it to function so I can install my 4 GB graphics card, which requires at least a 500w PSU.
Any help you can provide is appreciated, even if it's bad news. Thanks!