So I think I *may* have found the answer to this.
Bear with me, this is my first Hackintosh build, so I may say some things that make no sense… But I tinkered with this enough that I feel I may have found the source of the problem.
After turning off XMP and confirming that it was the source of the problem, I first tried
@danilovitch ’s solution and used Clover Configurator to activate XMP. About This Mac was indeed showing 3000 MHz, but I did a lot of tests, and I did not see an improvement.
I’m thinking you can’t activate XMP through Clover, is the BIOS is set to not overclock the RAM, then standard speed it is.
So I set out to do a manual overclock through the BIOS. Things got weird, sometimes things would work, I would try to change a simple setting and USB would start unmounting again.
Eventually, I figured out that MacOS behaved like this as soon as I went over 2666 MHz. Every other settings (volt, Enhanced performance vs normal, etc) made no difference (other than stability of the overclock).
After some googling, I found that 2666 MHz is the fastest RAM speed that Apple sells (on the iMac Pro), so perhaps that’s the reason why things are not stable once you go over that number.
So now I’m rocking RAM at 2666 MHz instead of the 2400 MHz base. Unfortunately my RAM is rated for 3000 MHZ, and using XMP, I was able to get it to 32000 MHz. On the plus side, I was able to get the timing from the suggested 16-16-16-39 to 15-15-15-35, so there’s that.
The good news is that my benchmarks show that I am still nearly getting the speed I was getting with XMP on (and even some better results in single core tests)!
Here are my results
Single Core Performance
Memory Copy
XMP off: 5870
XMP Profile 1:6859
Homemade: 6660
Memory Latency
XMP off: 6389
XMP Profile 1: 7602
Homemade: 7532
Memory Bandwidth
XMP off: 5060
XMP Profile 1: 5282
Homemade: 5832
Multi-Core Performance
Memory Copy
XMP off: 6892
XMP Profile 1: 8283
Homemade: 7874
Memory Latency
XMP off: 6427
XMP Profile 1: 7570
Homemade: 7525
Memory Bandwidth
XMP off: 5335
XMP Profile 1: 6606
Homemade: 6131
So if you still have that problem, I suggest trying to get your RAM to 2666 MHz and see if that helps. To get there, I had to use a Reference Clock of 133 Mhz in the BIOS, otherwise my choices were 2400 and 2800 MHz.
Of course if you bought RAM rated for 3000+ MHz, it can suck, but to me sleep and USB stability is more important, especially considering my benchmarks results.
Let me know if this helps!