550 Watts is the Nvidia recommended power supply for the system total. This is based of a 10900K Processor. Your requirements will vary since you have an older 9400 processor. You could give it a try, but it might not work well.   Personally I would opt for a 600 Watt power supply from a known manufacturer like Evga, Seasonic. I would advice against using some of the lower priced brands on Amazon, even if they are the "top seller". There's more to a power supply than power.    
Hello, I have an Aurora R8 with a i5 9400, GTX 1660ti,16gb of ram, and I believe a 460W power supply. I recently bought an RTX 3060 and was wondering if I will need to upgrade the power supply as well, or if I will be able to scrape by with what I have. I also have an added 2TB hard drive, if that would make any difference. Thanks for the help!
Aurora R8, RTX 3060 upgrade, PSU?