As a preface, my PSU is a 9 year old Gigabyte Odin 585, motherboard also 9 years old ASUS P7H55D-M EVO, and I have since experiencing this issue tress-tested with my old GTX460 1GB (dual 6-pin power connectors) on the same PSU+motherboard for testing purposes, without any issues, although to my knowledge that card cannot tax the PCI-E 'rail' my PSU may have as heavily as the RX570 could.
I bought a used (I'm the third or more owner thereof) ASUS RX570 4GB Expedition which I received on Monday. By 8PM I had it up and running and was testing some games on it. There were some performance issues and power consumption seemed to be limited to up to 129W peak, around 100W average, where I was under the impression the card could easily draw almost 200W under load, especially if that load is a heavy one. Temperatures easily rose to around 79C, and there were performance issues in games (erratic framerate drops/chopping even at settings which my GTX750Ti 1GB would do better at). This was with using settings like 'Chill' and/or the AMD framerate target setting, and without.
I removed the cooler and redid the still-stock TIM, which was thoroughly dry and judging by the ease with which the heatsink detached, no longer cohesive.
I reassembled, installed the card, ran some games tests and immediate impressions were that temperatures were substantially better. The computer was running fine for about 10 minutes, by which time I put the side-panel on, very lightly touching the rounding corner of the protruding PCI-E power cable. 10-15s later, my screen went black; on my G13 I could see the CPU and internet connection were still active, and there were no sounds from Windows as though something had been disconnected.
I pressed the power button for Windows to shut down, which it did (HDD activity and all).
Upon turning the computer back on, it began reporting there was no GPU attached.
I kept in mind I'd lightly scraped the power cable's side with the sidepanel and reconnected that; no go.
I completely reseated the card and the cable, after blowing out the port with a lens cleaner's blower; the card booted and I got into Windows. About 20-30s into being in Windows, while programs were still loading, the screen went blank again. This time, Windows hanged after about 5 seconds and eventually the computer switched itself off. Restarting, it once again reported no GPU.
I can, reliably, get the card to start up and display a picture for anything between 10-30s if it's not been running for a while and I try starting it up; but inevitably its fans switch off and on subsequent start attempts it'll either briefly power the card or won't even try.
I've already redone its TIM twice again just in case the cooler was somehow not making contact with the die, but the area behind the GPU and the heatsink remain quite cool, so I don't think the GPU is necessarily overheating... What I can say is that with the first application I evidently applied just a teeny bit too much of a highly-viscous one (Cooler Master's MasterGel as supplied with with their MA410P cooler), and a bit of it came into contact with the resistors(?) present on top of the GPU package. The entire package has since been thoroughly cleaned using absolute alcohol. I haven't gone anywhere near the VRMs and haven't taken off the heatsink there either.
So my question is, could this be little more than an issue of the PSU being too dated to supply the card with the juice it wants? Voltages in the two 2min OCCT runs I was able to do looked normal, though performance figures weren't with the framerate starting at 300fps for the first 20s and then dropping off to around 230fps thereafter in both runs. Voltage and current obviously not being the same thing, and OCCT doesn't report to me what the consumption was, I can only say what the AMD monitor told me (100-120w, with occasional 129W peaks)
I'm going to have the opportunity to test on a relatively-new PSU (Cooler Master GX II 750W) with four dedicated 6+2pin rail this weekend, so I'm *hoping* I'm dealing with little more than a PSU issue - but just in case there's some other reason the card might work on that system I'd like to know whether the sort of behaviour I'm experiencing could be PSU, PCI-E slot power supply or motherboard power supply in general related otherwise. I mightn't have the opportunity to test that PSU on my system overall to see whether there's a difference in that regard, I'll have to see how things go. If I can I'd like to forego buying a new PSU which mightn't solve my problem anyway, as I'm already out about $100 equivalent having just bought this card..
Thanks for any input, and sorry for the lengthy post.
NB: I note that in the OCCT tests the huge FPS drop (300 -> 230fps) seems to correspond with the CPUTIN and overall temperature going up markedly, however the core clocks across the board (X3460) were basically the same from the beginning of the test till its end, so I don't think the first 20s were it running a higher turboboost clock on some of them and then dropping to no TB...