I put together a machine powered by a Smart Pro RGB 850w, which I was quite happy with. I added a second GPU, and according to Outervision PSU calculator, my wattage load, should be around 848, and recommended a 1000w PSU. The system still boots and runs with the 850, but I'm slightly hesitant and afraid to run a stress test with it, and as I intend to add more storage anyway, I decided to get a Toughpower Grand RGB 1050. I intsalled it, tried to power up the machine, and the PSU just clicks, but doesn't turn the machine on. I got a replacement unit sent to me -- same result. I tested it with a small graphics card, and it does work then, but as soon as I add an RTX 3070, no joy. Same result with an iRGB Plus 1000w. Yet I can boot up both a 3070 AND a 3090 with the 850w PSU. It almost seems like there is some sort of fail-safe protection in the bigger PSUs that the 850w one doesn't have. That speculation is based on nothing -- this is my first build, and I'm very new to this stuff. Anyone have any idea what might be going on here? Oh, one other note -- I took the iRGB Plus 1000w to a local computer shop and had it tested, and they told me there is nothing wrong with it. Anyway, thanks for reading.