Question regarding RAM - PC clocks 2666mhz certain ram and 2133mhz on other

[kshantsilentk]

Hey,

HP Pavilion 590-p0066 Desktop PC

About a month ago I ordered DDR4 16GB Single 2666MHz (PC4-21300) CL19 Unbuffered
I took out the original Micron 4GB(2666mhz) and replaced it with the 16GB Teamgroup from Amazon,
So I now have the 16GB and the other original ram stick Micron 8GB (2666mhz) in

Last week I ordered 2 sets of 2x8
(1)Corsair Vengeance LPX 16GB (2x8GB) DDR4 DRAM 3000 (PC4 21300)
and 
(1)CORSAIR Vengeance LPX 16GB (2 x 8GB) DDR4 2666 (PC4 21300)

How come when I boot up with the16GB Teamgroup ram and 8GB Micron Ram, both 2666mhz, my PC will support the 2666mhz and run it at the speed, but when I put either one of those 16GB Corsair sets, both only ran at 2133mhz.

Thank you.

[Grzwacz · Accepted solution]

Hi,

Memory compatibility is a complex subject. HP does not support XMP in the BIOS. I believe 2133 MHz is the standard SPD for a Intel 300 series chipset. So any higher frequency achieved on a given stick of memory is technically overclocking.

Not all memory is created equal. I would guess for some reason the Corsair memory cannot clock higher than 2133 on your MB. Some older HP consumer motherboards would not POST when using various third party RAM modules.

Check out this entire article or watch the video (Link) by Gamers Nexus. Look at "SPD and XMP Explained" as well as all that follows.

Regards