RAM speed quirks

Hello, I'm running an HP-z620 hackintosh, Xeon 2643v1 3.3ghz 32 gb (8x4) ddr3-1866. C602 chipset.

My mobo/cpu combo should only get 1600 out if these dimms, and BIOS /Win10 shows 1600, but everything in macOs says 1866.

Also, I discovered this with a different memory stick. I have a 32g (1x) lrdimm rated 1600, which registers in Windows 10 and BIOS at 1333... And shows it as a 1600 mhz lrdimm in macOs. Same essential 'boost', or step up displayed.

I'm running high seirra, I haven't checked my catalina install, as I don't really use it.

My questions : Is this typical of macOs to get the RAM speed wrong in Hackintoshes? Is it actually running faster? Is there a Mac utility like z-gpu to look deeper? Geekbench doesn't show speed.

I plan on building an almost duplicate machine to this one so any info or peace of mind on the discrepancies I described would be appreciated.

I'm having no issues, mind you, just kinda driving me batty.