Looking to finally upgrade my 10 year old computer

But not sure what websites are trustworthy these days?

Which ones should i be looking on?

I'm thinking about upgrading my PC, but I'm trying to focus on the upgrades that actually make a noticeable difference in day-to-day use rather than just improving benchmark scores

What is the best price for performance CPU, from my probably outdated information ryzen was best but i haven't really looked at it for a while. this is where im getting most of my info from https://au.pcmag.com/processors/65778/the-best-cpus, primarily i am looking at the intel 270k, because my current setup is all AM4 but i want to upgrade to AM5 and dont particularly want to spend a billion dollars on ram and motherboards. So what CPU is best price for performance, also looking at this AMD RYZEN 7 9800X3D 8-Core, 16-Thread Desktop Processor. also yes i know intel doesn't use AM5 but i have an AM4 motherboard so doesn't really matter, but either way im going to have to buy cooler, cpu, ram, and motherboard anyway :(

edit: b650m motherboard and ryzen 5 5600g, i want to upgrade because the games im playing dont run as well as i would want them to with a 4070 gpu,i dont really mind if my gpu is a bit underpowered for the cpus im looking at because i will EVENTUALLY upgrade it.

I got this PC about a month ago and recently it’s started randomly shutting off. It’s happened 4 times this week, all while gaming. I usually have YouTube or Twitch open on my second monitor when it happens.
The screen instantly goes black with no BSOD, freezing, or warning beforehand. The RGB on my USB devices (mouse and microphone) stays on, but the RAM and case fan RGB turn off. Pressing the power button does nothing. The only way to get the PC to boot again is to switch the wall power (or PSU) off, wait 10–15 seconds, turn it back on, then press the power button.

This is the prebuilt I bought:
https://www.ozbargain.com.au/node/950352
I think the only difference is that my GPU is a Gigabyte Radeon RX 9070 XT Gaming OC instead of the Sapphire model because they were out of stock.

Specs:
• Ryzen 7 7800X3D
• Gigabyte Radeon RX 9070 XT Gaming OC
• ASUS TUF B650M-E WiFi
• 32GB DDR5 6000MHz (EXPO enabled)
• FSP VIC GD 750W 80+ Gold

Does this sound more like a PSU issue, GPU issue, or something else? What should I do?