Long story short I bought 32Gb of Trident RGB 3200 MHz from an auction site and was sent 16 GB of Trident Z Royal 4266 MHz CL 19-19-19-39 by mistake. My PC won’t boot with XMP enabled but I wondering if I can run at lower MHz and tighter timings - would 3800 MHz CL-17-17-17-36 be possible for example?
Set XMP enabled. While enabled, manually set the dram freq. to 4000mhz and see if it posts up. If it does, then start tightening the timings. Using 1.45v with that memory should be no problem. Running 17-17-17 4000mhz should be no problem. Or, you could incrementally increase DRAM freq. with 19-19-19 from 4000 up to 4267. But you gamble the memory controller can handle it.