[SOLVED] Should I upgrade a few parts or replace my whole computer?

[tofuDN]

I built my current rig myself and it is approx. 4 years old. Here are the components:
Motherboard - Tuf Gaming X570-PLUS
RAM - Patriot 4GB X4 for a total 16 GB
GPU - EVGA GeForce GTX 1070
Harddrive - Seagate Barracuda SSD 1 TB
Cybetron ATX Power Supply 500w
CPU - Intel Core i7-8700K 3.70 GHz with Cooler Master Hyper 212 EVO
DVD Drive - LITE-ON Technology Corp DVD/CD Rewritable (Yes I actually use it, mainly old games and DVDs)
2X Thermal Lake TT-1225 fans (It's what I could fit)

Maybe not the best, but it's what I could afford at the time. It doesn't seem like anything is running slow, but my RAM usage is 73% and there are certain games I can't play anymore without it crashing, freezing, etc. I've also been told that I have run out of space on my hard drive and my case fans have been running super hard for the past month or two and my CPU averages 51 C or 124 F which I know is high. I have considered adding a second hard drive, upgrading my RAM to 4 8 GB for a total of 32, and replacing all of my fans. However, if this would only be a "patch" to slow the inevitable, I'd rather rip the band-aid off then have to repeat the process in like a year.

EDIT Forgot to mention, it's clean as a whistle. I take it apart and clean it regularly, last time being yesterday.

EDIT Sorry for the confusion guys, I wrote down the wrong motherboard. Asus Tuf Gaming Z390-Pro. I also forgot to put the RAM type, which I cannot believe I actually did that, it's DDR4 2666 MHz Dual Channel The case is a repurposed cybertron case, I had one of their computers, hated it, built my own but kept the case and the power supply. All drivers are up to date and I clean and defrag regularly.

 

[Lutfij]

Welcome to the forums, newcomer!

Cybetron ATX Power Supply 500w
Repalce for a reliably built PSU with a higher wattage.

Your specs seem very off, you can't work with an i7 on that X570 chipset since they are both incompatible. Might want to revisit your specs with the right parts and then the community can chime in on possible upgrades.

 

[Lafong]

How much free space do you have on that SSD?

16 GB RAM is normally OK for most installations.

If you upgrade case fans and CPU cooler, you can likely knock temps down a bit and also carry those new components over to a new total rebuild at a later date.

What case are you using?

 

[DSzymborski]

Some clarity on the CPU/motherboard is necessary. RAM you've provided nothing but the amount. In other words, we're still missing a lot of basic information.

The PSU is absolutely horrifying and I can't believe you've been rolling the dice all this time with a GTX 1070. It ought to be replaced no matter what and immediately; I would never have even turned this PC on.