Having used Optiplex computers for a couple of decades for business clients, it really never occurred to me that one of these could be converted to a gaming computer.  But, there is a lot to like about this one.  First, the 9020 was one of the last desktop computers from a major computer provider (HP, Lenovo, etc.) that used mostly standard components.  The power supply is the standard ATX size, not the the small, odd shaped ones that are really, really hard to upgrade.  Secondly, the post pattern on the case match standard ATX mini boards.  The cutout in the back for rear ports is also standard.  Front panel connectors are another story.  USB 3 is standard but the power switch, audio and USB 2 ports are proprietary.  I wanted to put in RTX 3060 but the stock power supply was not going to cut it.  So I ordered the Thermaltake 600w PS and popped it right in, mounting holes matched right up, perfect fit.  YOU WILL NEED one of the 24 pin to 8 pin motherboard adapters for this to work.  There are quite a few of them for sale on Amazon.  Now, plenty of power to drive the RTX 3060.  You should be aware that the I7 processor in this one (4790) is NOT on the Windows 11 compatibility list and Dell has indicated it is not likely to write any drivers.  It is an older motherboard with an LGA 1150 socket, so your processor is already as good as it gets.  But if you are fine staying with Windows 10, this is the one.  My only complaint is that the back portion of the case where the add-in cards go was dented a bit.  I had to straighten it out with pliers in order to get cards to seat properly and the compression latch on top that Dell uses to hold add-in cards in place (instead of screws) does not work very well.  All in all, I am happy though.  Game on!