If you didn't need a graphics card which parts of a computer

>>56147343
SSD if you don't have one

CPU if you have a use for it

PSU would probably be my choice but a shit PSU killed my computer once so take that with a grain of salt

>>56147343
GPU is pretty much the only part of my current build that actually would benefit from being upgraded. Would prefer to invest in a better chair, desk and perhaps an extra monitor.

>>56147343
monitor

It depends on what kind of work you're doing.

Sound proofed mATX case, noctua CPU cooler, noctua ULV poop fans, PSU that doesn't spin until [x] load.
No hard drives at all, only SSDs.

Silent processorcooler, xeon instead of i7, ecc ram, silent case