Let me explain my needs & may be you can suggest what I need from hardware point of view. My software stores the tick data in one of it's folders on C: drive during market hours. I need random tick charts. ( e.g 500t, 1700t, 3000t, 7000t upto 25000t ). The software builds those tick charts from the tick data it has stored in one of it's folder. Right now I am using Dell T-7500 workstation with Xeon E5645 @2.4 GHz, 12 GB RAM, & it is too slow building those tick charts. So I need a faster rig. So what would you suggest ?
Since you specified 8GB total disk space, that led me believe that you are doing a lot of disk work. Also, for 256GB NVME is way too small for this system. Remember that Windows will also use this drive for swapping memory, which will certainly happen if you buy only 16GB or RAM.
What I suggest, you're not going to want to hear.... That is, stop doing tic charts. Do something longer. Archiving tic charts stresses the heck out of every aspect of your rig. Even 10-second charts would be a huge relief. Besides, tic charts are sooooo focused on the moment, it's easy to "not see the forest for the trees". Truth be known... you may not be doing tic charts even though you think you are. Years ago I had eSignal... they updated "only 6 times a second". Tics are waaaaaayyyy faster than that! IOW... eSignal was not reporting "tics"... they were reporting a "snapshot every 0.166 seconds".... which is more than fast enough for mortal retail screen jockeys like us.
It always depends of what you're using and doing. On my trading rig, I'm using 53% of 32 Gb of RAM. I do day trading, with IB Gateway/API, with IQFeed and proprietary trading software using NN and Machine Learning algos. In parallel of my real time trading, I'm always testing others algos. My previous rig had 12 Gb of RAM and it was always at the max. So again, it depends. But in regards to the OP needs, 32 Gb seems more appropriate. But like you say, it doesn't cost anything to start with 8 Gb and increase as needed afterward.
"More RAM is always better" is not a general rule. One needs to build his rig to accommodate his maximum use requirements.
I'm a KISS advocate. Read a story one time about some guy saying, "simplify your system as much as you think you can possibly can. When you're done doing that, simplify again!" I'm onboard with that. Trading usually requires some sort of simple rules and understanding so that we can actually execute. Easier to trade a simple system than a complex one.
Even ticks are not that cpu intensive, you have to identify bottlenecks. If vendor software is poorly written no modern hardware can help.