What computer to buy

Just got a Dell 9020 USFF a few days back, 80 Euro delivered with 4GB of RAM and a 500GB HDD, installed LinuxCNC with Mint 19.3, from a short test seems fine.

I am sure that two sticks of 4GB will be better than a single stick of 8GB as all processors from core2 i think use dual channel RAM access, but the difference is only noticeable on heavy memory use apps, and latency will be a bit lower always. It will not do miracles for latency, so a bad latency PC will have bad latency, except when a memory module already in use has issues causing latency excursions.
-it is always good to have another memory module to test with if the PC has bad latency,
-even a bad module when paired with a good one will help with latency,
-some PC just have bad latency, be it from bad memory lane design or lousy electronics or even worse power savings implementation, use of low quality power stages that cause the processor to throttle down whenever it tries to use more power, etc etc.
Oh, and then there are dual rank memory modules, not the same as dual channel, but only on new systems and works properly only on AMD systems as far as i could gather. I do have 2X16GB of dual rank on this PC (the mini monster), and i must say it is noticeable when using multiple apps at the same time.