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I have a new Dell Precision M4800 computer - the memory for it was spec'd at 1866MHz.

When I ran the Dell built-in (to the BIOS) diagnostics, though, it reported the memory speed is 1600MHz. This caused me some concern that perhaps I had gotten the wrong memory chips.

However, when I look at the system information in the BIOS Setup, it reports the memory speed is 1867MHz, i.e., the spec. So which is correct?

So I ran the diagnostic tool memtest86+ -- it reported 1600MHz like the Dell diagnostic.

Then I ran Speccy - it says the memory "DRAM Frequency" is 932.2MHz (which happens to be almost exactly half of 1866MHz). It also says it's "Dual Channel".

Is the spec'd memory speed of 1866MHz the product of the "DRAM Freq" times "# of channels"? if so, then Speccy would support that it is as spec'd.

But I still don't know why the built-in Dell diagnostic & memtest86+ both report 1600MHz.

So my questions are:

1) How can I definitively determine the RAM speed so I know if I got what I paid for?

2) Why do I get differing results from different tools?

EDIT 2014-04-09

I also ran CPU-Z as suggested in one answer and under "General" it reports "NB Frequency" is 799.0 MHz and under "Timings" it reports 932.2MHz (same as Speccy). It also reports "Channel #" as "Dual", like Speccy.

EDIT 2014-04-13

took out the memory & checked. Here are the pictures of both sides: enter image description here

enter image description here

According to the sticker it IS 1866MHz. So why do the diagnostics say 1600MHz? And does the processor really take advantage of the extra speed? If not, why do Speccy & CPU-Z give the better timings?

EDIT 2014-04-16

I found a Part Number Decoder at this address: http://www.skhynix.com/inc/pdfDownload.jsp?path=/upload/products/gl/products/dram/down/DDR3.pdf

According to that, the PBA appearing under the long part number in the photo above means that the chips are:

PB - 1600 MHz A - : Commercial Temp1) & 1.35 VDD (1. 0°C ~ 85°C)

If that is true, that explains why Speccy, CPU-Z and Dell Diagnostics report 1600 MHz as the speed. This suggests the sticker is mislabeling since it says 1866MHz. I still don't know how/why the Memory timings from Speccy & CPU-Z indicate that it is operating at (or close to) 1866MHz. Nor do I understand if the CPU can take advantage of the increased speed (if it exists).

I have written to the chip manufacturer to confirm I am decoding it correctly. I will also write Kingston.

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2 Answers 2

It sounds like they have installed 1600mhz sticks and overclocked them to 1866mhz. CPU-Z should give you the operating speed of the ram. As with speccy, some tools will show you half the speed because of the way RAM works. That's the speed per channel, but as it's dual channel you'll be getting double that, making the effective speed double the result speccy suggests. Some tools will query the RAM directly to see what the ram itself is and some will query the mobo to find out what it's running at. That's all I can think of I'm afraid.

Edit: If you know what you are doing, you can always take the PC case apart and check what it says on the side of the sticks.

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Thanks - I tried checking the sticks themselves, but unfortunately it appears they are installed under the keyboard. I was advised by Dell technical support not to try accessing them myself, but they said I can take the computer to their lab and a tech will check for me. I ran CPU-Z as you suggested - I've updated the question with those results. I will see what I learn when I'm able to get to the lab. You may be right about overclocking 1600MHz sticks. I will investigate further... –  yosh m Apr 9 at 14:01
    
OK - checked the sticks inside. See update to question with photos. It looks like they are labeled as 1866MHz. –  yosh m Apr 13 at 12:51
    
Then I'd say the other answer to this question is correct, In that 1866mhz has been installed but is limited by your processor to 1600mhz, so you'll be getting 1600mhz. –  Simkill Apr 14 at 9:53
    
But why do the timings shown by CPU-Z and Speccy indicate 1866MHz? That would seem to indicate they are actually running that fast, no? –  yosh m Apr 16 at 11:03
    
Also see the edit I just added to the question. –  yosh m Apr 16 at 13:30

According to the Dell website: "4 DIMM slots: up to 32GB 1600MHz; Or up to 16GB 1866MHz memory", so if you have 16G+ it's probably running at 1600MHz even though the memory itself is 1866 MHz.

You could also check the Intel specs for the CPU (at http://ark.intel.com), it will tell you what the maximum usable RAM frequency is. For the i7-4800MQ CPU it's 1600MHz.

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1  
Right track! That processor has a max speed of 1600MHz ark.intel.com/products/75128/… –  AthomSfere Apr 9 at 13:20
    
I have only 8GB of memory - it should be running at 1866MHz - if it is as spec'd. –  yosh m Apr 9 at 13:54
    
I know it should be. Could you check your exact CPU model against the information in Intel ARK. The only info I could find was that the M4800 has an i7-4800MQ CPU, which only supports RAM up to 1600MHz. Any faster RAM will just run slower on this CPU. This would explain the difference, because the DIMM's still support 1866, the CPU just doesn't use it. –  mtak Apr 9 at 13:58
    
I have i7-4700MQ. Under Memory Types, ARK says "DDR3L-1333,1600". I presume this is consistent with what you said about the CPU not supporting faster than 1600. However, it seems odd that Dell would be so disingenuous as to write in the specs (as you noted) "up to 16GB 1866MHz memory". If they're not going to use the speed - they could have advertised up to 32GB at the faster (but unused) speed. –  yosh m Apr 9 at 14:13
    
BTW, if the CPU is not capable of handling faster than 1600 (as suggested by the ARK database and by CPU-Z's reporting dual channel @ 799MHz for the Northbridge frequency) - then how could the timing report a faster frequency (932.2, dual channel)? Do they overclock? Is 1600 "nominal" while the faster speed is "actual"? –  yosh m Apr 9 at 14:20

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