Identical RAM not running at the same speed

[NPSTR107]

I rebuilt my current PC about two years ago with 2x16GB DDR4-3600, G.Skill Trident Z Neo, Model F4-3600C16-16GTZNC, and all was running well.

 

I recently decided to double my RAM with the same identical set as above (exact same model number) however, all the speeds are all over the place, and I don't know how to fix it. I don't know overclocking and I'm not brilliant with BIOS stuff.

 

Shouldn't all the speeds be 3600 MHz?

 

CPU-Z shows slots 1 & 2 as running 2666 MHz, and slots 3 & 4 as running 2132 MHz.

The BIOS shows DIMM A1 & B1 as running 2666 MHz, and DIMM A2 & B2 as running 2133 MHz.

 

Screenshots of CPU-Z and my BIOS are attached, and my current system specs are as follows.

 

CPU: AMD Ryzen 9 3900X 12-Core

MOBO: ASUS TUF GAMING X570-PLUS (WI-FI)

RAM: G.SKILL TRIDENT Z NEO 4x16GB DDR4-3600

GPU: NVIDIA GeForce GTX 1080Ti

PSU: Corsair RM850

 

Help / advice appreciated. Cheers.

 

[Zando_]

You're looking at the CPU-Z readout for the specs of the DIMMs, I believe the "Memory" tab is the one you want, not SPD. RAM should be running at ~1800Mhz there if it's working right. 

[RONOTHAN##]

12 minutes ago, NPSTR107 said:

the same identical set as above (exact same model number)

Same part number does not mean that the RAM is the exact same. There are a lot of different memory ICs that can do the same settings, and not all of them play nicely with each other. 3600 CL16, for instance, has something like 6 different ICs that can exist on it, and if you look in that CPU-Z screen shot you'll see that one of the DIMMs is single rank while the other one is dual, meaning that your sticks are in fact very different from each other. It still can run at the exact same speeds, but you're a lot more likely to run into issues with that. 

 

Anyway, there's conflicting information in that one BIOS screen shot, where it's saying that the RAM is running at 3600 in the first half, but the second half is listing a bunch of different JEDEC speeds, which would lead me to believe that the second half is just listing the JEDEC values of the memory sticks. Head over to CPU-Z and read the memory tab as that will show you what the RAM is actually running at. The other option is to download a program called ZenTimings as that will generally get more information about what the memory is actually running at, though it can only read memory ratios so it's not as reliable at reading exact memory frequency as CPU-Z is. 

[NPSTR107]

26 minutes ago, Zando_ said:

You're looking at the CPU-Z readout for the specs of the DIMMs, I believe the "Memory" tab is the one you want, not SPD. RAM should be running at ~1800Mhz there if it's working right. 

 

Screenshot below, seems to be at 1796.4 MHz.

 

6 minutes ago, RONOTHAN## said:

Same part number does not mean that the RAM is the exact same. There are a lot of different memory ICs that can do the same settings, and not all of them play nicely with each other. 3600 CL16, for instance, has something like 6 different ICs that can exist on it, and if you look in that CPU-Z screen shot you'll see that one of the DIMMs is single rank while the other one is dual, meaning that your sticks are in fact very different from each other. It still can run at the exact same speeds, but you're a lot more likely to run into issues with that. 

 

Anyway, there's conflicting information in that one BIOS screen shot, where it's saying that the RAM is running at 3600 in the first half, but the second half is listing a bunch of different JEDEC speeds, which would lead me to believe that the second half is just listing the JEDEC values of the memory sticks. Head over to CPU-Z and read the memory tab as that will show you what the RAM is actually running at. The other option is to download a program called ZenTimings as that will generally get more information about what the memory is actually running at, though it can only read memory ratios so it's not as reliable at reading exact memory frequency as CPU-Z is. 

 

Hmm, ok. Probably should have researched more before buying them, I didn't know that.

 

What do you think of the screenshot below? And are there any BIOS settings that may improve my situation?

 

 

[Zando_]

1 minute ago, NPSTR107 said:

Screenshot below, seems to be at 1796.4 MHz.

Yep, running 3600MT/s then (effectively 3600MHz which is why they put it on the box/in the BIOS/etc). The BIOS showing the same speeds as the SPD readout is likely it doing the same thing as that SPD panel, just reading the base specs off each set of DIMMs, not the speed they're actually running at. 

[RONOTHAN##]

Just now, NPSTR107 said:

 

Screenshot below, seems to be at 1796.4 MHz.

 

 

Hmm, ok. Probably should have researched more before buying them, I didn't know that.

 

What do you think of the screenshot below? And are there any BIOS settings that may improve my situation?

 

 

Yeah, that confirms what I said, it's running at 3600MT/s (DRAM frequency is half the speed of the effective frequency because RAM is double data rate), so that section in the BIOS is just reporting what the JEDEC speeds of the particular kits. 

 

Nothing to worry about, your RAM is running at it's rated settings.

[NPSTR107]

6 minutes ago, Zando_ said:

Yep, running 3600MT/s then (effectively 3600MHz which is why they put it on the box/in the BIOS/etc). The BIOS showing the same speeds as the SPD readout is likely it doing the same thing as that SPD panel, just reading the base specs off each set of DIMMs, not the speed they're actually running at. 

 

5 minutes ago, RONOTHAN## said:

Yeah, that confirms what I said, it's running at 3600MT/s (DRAM frequency is half the speed of the effective frequency because RAM is double data rate), so that section in the BIOS is just reporting what the JEDEC speeds of the particular kits. 

 

Nothing to worry about, your RAM is running at it's rated settings.

 

Great to hear, thanks for your help!