Question Memory speed question

[JudMc]

On a Sandy Bridge CPU, some memory runs at 666MHz and as 9-9-9-24 CL, etc. Other runs at 800MHz and has 11-11-11-28. 9 clock cycles at 666MHz is almost exactly the same as 11 clock cycles at 666MHz. Does that make the overall memory speed about the same, or is one of them faster enough to matter?

 

[Lutfij]

Welcome to the forums, newcomer!

The memory speeds will depend on the chipset of the motherboard for that era/platform. If you have a non P67/Z68 chipset board, the maximum ram speeds you're going to see is DDR3-1333MHz(divide by 2 to get the speed you're seeing above). The P67 and Z68 chipsets offer to overclock the rams which is why you see higher frequency's than DDR3-1333MHz.

On that note, if you intend to tighten the timings on the rams while keeping the frequency the same, it's the same as overclocking, you might need to add some voltage to the ram kit...i.e, 1.65v as opposed to 1.5v when running at DDR3-1333MHz however the functionality in your BIOS and the power delivery on your board will dictate your mileage with ram overclocking.

With all that being said, what platform are you working on?

Please include your system's specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Case:
OS:

 

[JudMc]

I don't know much about motherboards and chipsets. These are two Sandy Bridge HP Z420s. The documentation says: PC3-12800E 1600MHz DDR3. Then it says that 1600MHz, 1333MHz, and 1066MHz are supported.

I don't seem to be getting the memory speeds the docs say.

#1:

CPU: Xeon E5-2680
MB: HP 1589
RAM: 8x4GB, 800MHz, 11-11-11-28 (from Speccy)
SSD/HD: ADATA SU635 480GB
GPU: NVidia GeForce 8400GS
PSU: HP
Case: HP
OS: Windows 10 pro 64-bit

#2:

CPU: Xeon E5-2690
MB: HP 1589
RAM: 4x8GB, 666MHz, 9-9-9-24 (from Speccy)
SSD/HD: Seagate ST1000
GPU: NVidia GeForce GT 710
PSU: HP
Case: HP
OS: Windows 10 pro 64-bit

---------------------------
Several hours later:

Well, I found out that Task Manager/performance/memory also gives the speed of the memory bus. I tried it on four computers, and in all four cases, it showed twice the speed as Speccy shows (1333 vs, 666 and 1600 vs. 800). So maybe Speccy is reporting half of the actual speed.

So back to the original question, is there much of a difference between 800MHz, 11-11-11-28 and 666MHz 9-9-9-24?