[SOLVED] DDR3 2x 1066 + 2x 1600 results in 401 MHz and not 533 MHz in CPU-Z. Do not understand why...


Dec 23, 2020

I am not an expert with memory, but did a lot of searching/reading before buying/adding memory on my PC.

Fortunately, it works, but I do not understand the shown frequency in CPU-Z and wondering if something is wrong.

MoBo: ASUSTeK Computer INC. P8P67 PRO (LGA1155)

I had 2x DDR3 4096 Mo Patriot Memory PC3-8500F (1066 MHz) 1333EL Series XMP.
I added 2x DDR3 8192 Mo Corsair PC3-12800K (1600 MHz) CMV8GX3M1A1600C11.

So I have 24MB and it is working. I also understand that the frequency is limited to the slowest DDR3 one. I also understand that CPU-Z is showing half of the frequency. So with the initial setup (2x DDR3 4096 Mo 1066, CPU-Z was showing frequency of 533, Win10 was showing 1066 ).
Now with the new setup, CPU-Z is showing only 401.4 MHz and not 533 (half of the slowest of both DDR3). I do not understand why... Windows on the other hand is showing a speed of 800 MHz...

  1. can someone explain the 401.4 MHz shown by CPU-Z?
  2. should memory sticks be put in a specific slot? I mean the fastest in slots A or preferably in B? Or does this have no impact at all
  3. any advice for tuning this setup in the BIOS?
Many thanks in advance!