update or replace

I would probably lean towards a new system. The GPU in a system that is 10 years old is certainly not supported. More RAM will help, but a new faster CPU with the same RAM upgrade will blow the doors off your old system. SSD drives are almost standard in modern computers, too. Disk speed is crasy fast with SSD.

Adding RAM will help, but keep in mind that today's applications rely heavily on the video cards. 

Warmly/j

Go with the best you can afford. I like purchasing high end Dell refurbished workstations from

Dell Outlet that I can afford without robbing a bank. my budget range  is $1,500. to $2,500.  I look for workstations First with Fast CPU and RAM Clock Speed ( with reasonable price point CPU speed is major price factor).  Second SSD you want  System and Application  data, Paging, Temp Space, Scratch Space on SSD ( I keep my User files and backup on externals  USB 3 hard disk),   Modern Fast  supported GPU and at least 16GB of ECC RAM.    RAM and can easily be Added and GPU can be easily replaced  if needed.  I tend to look for machine that have Nvidia Quadro display Adaptors they seem to have better supported device Drivers for I do not see users in the Photoshop forum  reporting their quadro GPU is not support or recognize by Photoshop.  Adobe also seem to recommend them for their video editing applications like Premier Pro.

Dell refurbished workstation come with System Installed and a Dell three year in house repair warranty.  Over the years I have purchased  three dell workstation and 5 home machine and always found  Dell support very good,  but have had little contact with Dell for I needed little help.  However, one of the Workstation Failed within a month of Purchased.  I call Dell over the Phone we determined it was a Mother board problem. A Dell service  rep was in my house the next day replaced and tested the mother board replacement. That workstation is now four years old  and the other two are older.  One of them had a quadro 4000 go bad. I replaced it with a cheap Amazon refurbished Quadro k2200  that Dell workstation is now 8 years old  it came with 8GB of Rams I added 32.  I use it daily. But its slower than you maniv it has tweo 6 Cored xzon Processore onle 2GHZ.   A single  processor with faster clock would have been better,  Referbished Dell  Worstation are not always available and it was all I could affore 8 years ago that had an SSD on Dell outlet. Current outlet supply is very poor... I see one machine available.

https://www.dellrefurbished.com/item/dell-precision-5810-tower-5f72518d/dell-precision-5810-tower/1.html?child=dell-precision-5810-tower-000187&p=1 

Dell has now lowered the  support from 3 years to 100 Days that poor....

New workstating starting point would be $2,500 these days for me.

Windows 10 task manager will tell you how many ram slots you have

If you haven't already I'd stick an SSD into the PC as well

Hi John Dudley,

adding additional RAM is certainly a great help. To check if you can add additional RAM in your configuration, you need to check if there are additional slots on the motherboard to add more RAM banks.