XPS 8930, retail Corsair memory, maximum frequency?

Look at specs of your memory here: https://www.corsair.com/ca/en/Categories/Products/Memory/VENGEANCE%C2%AE-LPX-16GB-%282x8GB%29-DDR4-DRAM-2666MHz-C16-Memory-Kit---Black/p/CMK16GX4M2A2666C16

Notice that the SPD Speed is 2133 MHz and the Tested Speed is 2666 MHz. The Dell BIOS does not have any features for looking at the XMP 2.0 profile of the memory or a way to adjust the speed. There was a post in this forum where someone was able to use Intel's Extreme Tuning Utility (XTU) to get the higher speed. I am afraid you are stuck at 2133 MHz unless you can get XTU to work.

SepehrZ, sorry this post is a little late but I could not see the photos from your original post. Now the photos are available and I noticed that where it says "Ranks" it says "Single". That tells me that your memory sticks are not installed as matching pairs in the proper slots. Matching memory sticks should be installed in the memory slots with similar colored securing clips (both white or both black). If properly installed the "Ranks" should say "Dual". "Dual" outperforms "Single".

Are those Corsair modules single rank or dual rank? I see some sites saying they're single rank, searching on the part number shown in your jpg, which agrees with CPU-Z.

BTW: You have to multiply the RAM speed (max bandwidth) shown by CPU-Z by 2, the "multiplier", in order to get the actual speed of each RAM module.

Corsair module in slot 1 is detected by CPU-Z as 1066 MHz (times 2 = 2132 MHz, not 2666 MHz you indicated), and the Micron module in slot 2 is detected as 1333 MHz (times 2 =2666 MHz). So all RAM will run at the speed of the slowest module, 2132 MHz.

So something ain't right. Matched RAM modules should be in slots with the same color retention clips, and slots may not be numbered sequentially, so check the XPS 8930 service manual for their actual numbering.

If you install only the Corsairs in slots 1 and 3, with the same color retention clips, what does CPU-Z say now?

According to the tech specs here: https://www.corsair.com/us/en/Categories/Products/Memory/VENGEANCE%C2%AE-LPX-16GB-%282x8GB%29-DDR4-DRAM-2666MHz-C16-Memory-Kit---Black/p/CMK16GX4M2A2666C16

the Memory Configuration is listed as Dual/Quad Channel.

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@Vic384 wrote:

According to the tech specs here: https://www.corsair.com/us/en/Categories/Products/Memory/VENGEANCE%C2%AE-LPX-16GB-%282x8GB%29-DDR4-DRAM-2666MHz-C16-Memory-Kit---Black/p/CMK16GX4M2A2666C16

the Memory Configuration is listed as Dual/Quad Channel.

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That may be true, but "dual rank" isn't the same thing as "dual channel". The Corsairs could be single rank, dual channel modules.

Single rank typically meant memory chips on only one side of the RAM module's PCB board, and dual rank meant chips on both sides of the RAM PCB board, but that definition has blurred in recent years.... 

The OP needs to look on the Memory tab in CPU-Z to see if the installed RAM is running as single- or dual-channel memory, which is what's important, and to see if there's a difference on the Memory and SPD tabs for each pair when only one matched pair is installed in the correct modules at a time.

As it stands now, CPU-Z doesn't report the "correct" max bandwidth for the Corsairs, so that's why the pairs should be tested separately.

Ron, I agreed with you about "dual rank" not being the same as "dual channel". I also agreed with you that the OP should look at the Memory tab of CPU-Z; I am pretty sure it will indicate that the DRAM frequency is 1066 MHz. The question is what does Channel # on the Memory tab indicate. But I think that CPU-Z is reporting the correct max. bandwidth because the spec SPD speed of the Corsair memory is 2133 MHz.

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@Vic384 wrote:

Ron, I agreed with you about "dual rank" not being the same as "dual channel". I also agreed with you that the OP should look at the Memory tab of CPU-Z; I am pretty sure it will indicate that the DRAM frequency is 1066 MHz. The question is what does Channel # on the Memory tab indicate. But I think that CPU-Z is reporting the correct max. bandwidth because the spec SPD speed of the Corsair memory is 2133 MHz.

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When the Channel # box on CPU-Z Memory tab says "dual", the RAM is running in dual channel mode. If it says "single" the RAM is running in single channel mode and not taking advantage of the extra speed offered by dual channel.

The OP said "The newly added sticks are CORSAIR Vengeance LPX 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 2666MHz (PC4 21300)." But CPU-Z is only reporting max bandwidth for the Corsair module as 1066, equating to 2132 MHz. If that RAM is really 2666, its max bandwidth should be 1333, just like CPU-Z reports for the Micron module in the other slot. So something isn't right..

I guess it's possible the Corsair and the Micron RAM aren't fully compatible with each other, or the Corsair with this motherboard, so that's why it's important to test the Corsair pair alone. If it's still reported by CPU-Z as a max bandwidth of 1066...??

My point is that while the Corsair memory may say DDR4 2666 MHz the specs say that is the Tested Speed. The SPD Speed is 2133 MHz. If the XPS 8930 BIOS could read and use the XMP 2.0 profile the OP may be able to achieve 2666 MHz with this memory but the BIOS cannot so he is stuck at 2133 MHz. In another post on this forum, someone else had this same exact issue and the only way he found around it was to use the Intel Extreme Turning Utiltiy (XTU). See here: https://www.dell.com/community/XPS-Desktops/XPS-8930-Corsair-LPX-DDR4-26-running-at-2133MHz/m-p/6131470#M16142

Your recommendation of testing the Corsair memory by itself will probably prove this.

Hi Ron, 

Thank you for your feedback. I did not have access to my desktop on the weekend. Per your suggestion I have tested the memory speed when Corsair memories where installed alone (slot 2 and 4). I am attaching the pictures showing memory and SPD tabs of CPU-Z using this configuration. I am still seeing 1064HHz. As@Vic384 suggested, the reason might be BIOS not being able to read XMP information. 

Could this be fixed with a BIOS update from Dell?

Thanks

The ability of BIOSs to read XMP has been around for awhile and if Dell did not implement it initially in their BIOS I doubt they will do it in an update. This is not like an error that needs to be fixed but a feature they decided to leave out.

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@SepehrZ wrote:

Hi Ron, 

Thank you for your feedback. I did not have access to my desktop on the weekend. Per your suggestion I have tested the memory speed when Corsair memories where installed alone (slot 2 and 4). I am attaching the pictures showing memory and SPD tabs of CPU-Z using this configuration. I am still seeing 1064HHz. As@Vic384 suggested, the reason might be BIOS not being able to read XMP information. 

Could this be fixed with a BIOS update from Dell?

Thanks

 

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How are the slots being counted here? Is CPU-Z numbering them as physical slots, counting from the CPU? DIMM1 is the second from the CPU, and DIMM2 is the fourth from the CPU according to the Service Manual.

You might dump the Corsairs because they'll probably slow the Micron modules down to 2132 even though CPU-Z sees the Micron as 2666. If you need more RAM, you might buy another pair of Micron which actually owns Crucial and sells RAM directly online at crucial.com, or from Dell Spare Parts which might cost more.  :Wink:

I have an XPS 8910 and I believe the memory slots are numbered the same as in the XPS 8930. DIMM1 (labelled XMM1 on the motherboard) corresponds to Slot #2 in CPU-Z and DIMM2 (XMM2) corresponds to Slot #4 in CPU-Z.

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@Vic384 wrote:

I have an XPS 8910 and I believe the memory slots are numbered the same as in the XPS 8930. DIMM1 (labelled XMM1 on the motherboard) corresponds to Slot #2 in CPU-Z and DIMM2 (XMM2) corresponds to Slot #4 in CPU-Z.

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That makes sense, just wanted to make sure the Corsairs were tested in the right slots.

Never have understood why CPU-Z will number slots literally rather than based on their motherboard/BIOS assignment...

Here is another bit of information, HWiNFO64 refers to DIMM1 as Row 1/ Module Number 1 and DIMM2 as Row  3/ Module Number 3.