Only atx 3.0 can deliver the full 600w threw the new connector and 1200w min to achieve that.
Big Tx to
@Haz123 in another thread making it clear.
Older ATX 2.0 psus will also deliver 600w with the adaptors for the 12vpwr connector , everyone just loves those. The ATX 2.0 psu and gpu do not comunicate with each other and the gpu will just draw as much power as it needs and if the psu is not capable of handling the power draw the OVP protections will trigger , hopefully.
The newer ATX 3.0 psus communicate with the gpu and the 850w and 1kw models will self limit to 300w and 450w respectively whilst 1200w and above can deliver the full 600w. I think this is a dirty trick by the industry with built in upselling marketed as a safety measure.
If you consider a system such as 5800x3d with 4090 , I would think there are thousands of systems like this in the world. If a person then had a 1kw atx 3.0 PSU and 600w was being used for the gpu that would leave 400w for the cpu and rest of the system, 150w for the cpu so 250w is more than enough for 99% of systems. No reason a person should not be allowed to get the full 600w for the gpu from a 1kw psu other than forcing them to buy more expensive psu earns the companies more money.
Whilst I do not want to see gpus using over 450w I do not think it good for us , the consumers, that the industry has introduced this "safety feature" and it is purely to sell more higher tiered products when they are just not needed
If I was buying a new psu in the 12-1500w range I would wait for the newer atx 3.0 versions to all be available. Hardwarebusters on youtube is an excellent channel to get psu advice from. Aris has a very strong accent but you can just skip to conclusion and follow his advice imho.
Your current psu would most likely work just fine with most 4090s, older ATX 2.0 design so it will not be limited to 300w by its 850w rating and most 4090s do not need anywhere near 600w. Unless you get the Gigabyte Master, FE or Strix then most 4090s are limited to 450w and your psu should be fine. I would buy gpu and test and if it shuts down then you need a new psu to run it.
