Psu 450w for optiplex 9020

1. Index is not a good name brand. This model got a terrible review.
2. it looks like a very old ATX psu model much older than 9020
3. Technically if you have 9020mt you can use any ATX psu+ 24-8 pin adapter. If you have 9020sff then no.

Red is correct. According the PSU Cultist Tier List, it's an "F" tier rating, meaning replace it immediately. Any PSU older than 2010 should be replaced. As for what power supply that can be used on the 9020 (assuming it's the MT), you can use either the stock 290W PSU, 365W supply, or any modern aftermarket supply + a 24 to 8 pin adapter. New aftermarket 500W PSUs are about $50, depending on what you want to use it for.

If you have the SFF, then you are limited to the stock proprietary  255W PSU, or the 315W Unit out of an XE2 SFF (VX372).

@CBIVTI22​ I’ve read online that you can only use certain kinds of psus on the 9020 mt and you can use any kind of psu but I’m not totally sure. I need to buy a psu to replace the stock one but I don’t wanna fry my motherboard. Which psus are compatible with a stock 9020 mt?

@Max37773​ You can do either a 365W PSU (Dell P/N 7CR3P, about $40 on eBay) or if you have a video card for gaming, I would recommend the EVGA 700BR PSU (available here) and the 24 to 8 pin adapter. Please note that if you do the latter, you might have to modify the case latch since I read that the aftermarket PSUs are ever so slightly wider then the stock PSU.