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I checked my RAM speeds in CPU-Z and noticed that they were lower than they should be. I've looked at related threads (e.g. this and this) but they didn't have the same problem as me.

Both my RAM sticks are DDR3 and supposed to run at 1600 MHz. Becuse CPU-Z reports actual RAM speeds, I'm expecting to see 800 MHz on both.

The problem is that on the JEDEC #3, 4, 5, 6 fields, it's reporting frequencies significantly lower than 800 MHz.

As expected, JEDEC #5, 6 on slot 1 and JEDEC #6 on slot 2 report 800 MHz. I know that the speeds can sometimes be lower, so that 700-ish speeds didn't surprise me. What surprised me though are the 609, 640, and 685 MHz readings. Those three readings suggest that those 'JEDEC's (no clue what that means) are running at or even slower than 1366 MHz.

Does anyone know what could cause this? Is it a cause for concern?

Here are screenshots of both sticks:

Slot #1:

enter image description here

Slot #2:

enter image description here

harrymc
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jdabtieu
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  • The SPD fields are just what the memory is *capable* of. Your system memory will be shown on the "Memory" tab in the "Timings" section. "DRAM Frequency" will show your actual speed. Your final speed will be a blend of the maximum speeds of the various speeds that each module are capable of. – Mokubai Feb 22 '21 at 20:02
  • @Mokubai so if the final speed is the max each module is capable of (i.e. 800 MHz), then does that mean that the lower speed parts only get used when the faster 'JEDEC' parts get filled up? I'm not sure I understand. – jdabtieu Feb 22 '21 at 20:23
  • "when the faster 'JEDEC' parts get filled up?" - What do you mean by this statement exactly? – Ramhound Feb 22 '21 at 20:40
  • I don't exactly know what JEDEC is, I assumed it was like memory cores, each one having 2GB capacity. However, harrymc's answer clears that up, and I understand what it means now. – jdabtieu Feb 22 '21 at 20:44

1 Answers1

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Your RAM comes with several JEDEC profiles, some of which are shown by CPU-Z. These are the profiles that your RAM is capable of running at.

The motherboard will choose among these JEDEC profiles the one that it prefers using, in view of the motherboard's capabilities and the JEDEC profiles of all the other RAM sticks.

Which JEDEC profile was chosen, can be derived from the Memory tab of CPU-Z.

harrymc
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