hi ok there are a few problems, ideally you want a blower GPU. Or an efficient low power card that is not going to test your cooling.
https://www.amazon.co.uk/ZOTAC-GeForce-2080-Blower-Graphics/dp/B07PJ45M9G
this was the first I found not a recommendation. Just for type.
Next if your G20CB has no jumper as shown in other posts to activate a second power supply then it’s tricky,
the jumpers if like mine are all down with no extra jumper above it then, so far I haven’t seen a hint on the forum, as a gambler I altered the one next to the R20 the one I think is labelled JDC01 so it in the top position this at least got the 180w power supply to warm up a little so it’s done something, but I am not sure what.
I picked a RTX 4060 ti founders addition as my upgrade as it has far lower power consumption at only 165w but it’s not a blower so not perfect, it fits if you buy the little 180 degree power connector adaptors https://www.amazon.co.uk/dp/B0C4PGS4QL?psc=1&ref=ppx_yo2ov_dt_b_product_details
for my card this was the correct one but there are others for other cards including standard 6 and 8 pin GPU connections to help with the wiring. On bigger cards but stick to 40mm thick or your in trouble (2 slots, not 2 and a bit)
so I run a 230w power supply and a 180w one which is what the system was designed to run on.
others may do things differently but that how I have set mine up.
I did add an m.2 drive a 980 standard 1T which needs a heat sink or heat sink fan combo, you have around 15-18mm of head room over the m.2 when it’s installed.
I ended up making a custom heat sink from an old GPU I had in my stash as it had a fan and heat sink and used a thermal pad and rubber bands to hold it in possition.
powering it was from one of the ssd power outs the one near the GPU slot as just had it spin all the time, it also cools the chipset passive heat sink.
the power for the fan will need something that doesn’t seem to exist.
I used a few old motherboard case wires the ends that plug into motherboard pins as singles. This makes it either 5v or 12v depending if you use red for 5v or yellow for 12v.
note the colour on the wires not the order, on our g20cb system they are non standard order.
note the colours and positions on the systems ssd power outs they can only be fitted one way as they use 5 pin plugs with only 4 pin holes and one missing pin on the board.
then I had a always on fan and the m.2 drive, and a ssd in the top slot above the CD drive.
this also gives more room under the GPU for cables.
