jupo

update: all of my adapters have arrived from both Amazon and Ebay. The first adapter to arrive was from Amazon by Adaptare. This does not work reliably. Sometimes the computer turns on, but most of the time it just tries to turn on and gives up. It may be my fault with a poor rewiring job. The ebay adapters also arrived (https://www.ebay.com/itm/ATX-24pin-to-Motherboard-2-port-6pin-Power-Supply-Cable-for-HP-Z220-Z230-SFF/181956988416), and after rewiring, this works perfectly. One press of the power button and the computer boots up immediately as expected.

Hi Jon I hope I can shine a ray of hope in your project. I bought the HP Elite 8300 (convertible minitower) super cheap for the exact same reason. Upgrade PSU and GPU for gaming. As far as I know, the 8100, 8200, and 8300 use the same PoS proprietary power supply and connectors on the mobo. Fortunately, there are adapters out there for people like us! Go on ebay or amazon, and search for "24 pin to 6 pin power adapter z220". The specific one I ordered from Amazon is made by Adaptare, but I hear the ones on Ebay from the maker AYA are good and popular. Adaptare: https://www.amazon.co.uk/dp/B01J9PCDMY AYA: https://www.ebay.com/itm/152350662741 These adapters are actually meant for other models of HP prebuilts (z220 and z230), so the connectors are the same, but the pin configurations are a little different. We need to rearrange the wires that come out of the white connector on the adapter for it to work with our 8200/8300s. It's explained quite well in the following youtube video: https://www.youtube.com/watch?v=xeuPjgIcsY8 I looked all over the web for these pin reconfigurations, and people are suggesting different things. I'm assuming it's because different adapter makes have different configurations. However, I found these two schematics that should help: One schematic: And another schematic: In both the schematics, you can see that the purple wire comes out of the 24pin +5 volt standby connector, then go to a step-up converter. This is because with standard ATX connectors, the standby (SB) is run with 5 volts. However, HP decided to screw standards even further by requiring a 12 volt standby! Luckily, the adapters I mentioned above already come with the step-up converter, which is the big black bulge in the middle of the wires covered in shrink wrap. Also, the wires coming out of the 24-pin grounds (COM) are a little different in the two schematics, but the PWR_OK and PS_ON are the same in both, which I think are the important bits. Finally, I'll tell you about my current status. I have my HP Elite 8300, new PSU (EGVA 650 G3) and new GPU (RX580), but I'm still waiting for my power adapter to arrive. So all this info I've gathered hasn't been personally tested yet . I ordered two different adapters from ebay, but the shipping was taking so long that I got impatient and ordered the one from Amazon with expedited shipping. It should arrive in about 4 days (Dec 5), then the fun begins. Hope it helps! Keep us posted, and I will too. Don't give up