gpu-z showing wrong memory clock

[Jun Wei Goh]

hi guy gpu-z is telling me the wrong memory clock speed is this a bug? MSI afterburner are reporting the correct memory clock same goes to the super composition benchmark my gpu is a msi gtx 1080ti gaming x

AM i right or is there something else? 

[Crunchy Dragon]

GPU-Z did that to me for a while, it was reporting that I was running at stock settings despite having an overclock. If I recall correctly, a restart and (possibly) a reinstall fixed that problem.

[KarathKasun]

GPU-Z is correct and AB is correct.

 

GDDR5 uses a clock quadrupled signaling scheme.  GPUZ is telling you the actual frequency of the memory chips, AB is telling you the clock speed of the memory bus.

 

If you multiply the GPU-Z clocks by 4 you magically arrive at the number that AB is showing.

[Oshino Shinobu]

GDDR5 actually has 4 clock speeds that can be quoted, the differential command clock (CK), two write clocks (WCK01 and WCK23, though they both run at the same speed) and then the effective clock. Programs like GPU-Z and CPU-Z tend to show the physical clock of components rather than any effective clocks, which is what it's doing here. 

 

The clock that is shown here is the CK. The write clocks run at double this speed and DDR takes that up to the effective clock that is quoted and shown by most overclocking software. 

 

Despite what you may hear, GDDR5 isn't actually a QDR memory type, despite the effective clock being 4x that of the CK, it's only DDR. GDDR5X can run as DDR or QDR, but GDDR5 is DDR only. 

 

TL;DR: It's showing the correct speed, it's just showing the physical/actual clock, while Afterburner is showing the effective clock. 

[KarathKasun]

3 minutes ago, Oshino Shinobu said:

GDDR5 actually has 4 clock speeds that can be quoted, the differential command clock (CK), two write clocks (WCK01 and WCK23, though they both run at the same speed) and then the effective clock. Programs like GPU-Z and CPU-Z tend to show the physical clock of components rather than any effective clocks, which is what it's doing here. 

 

The clock that is shown here is the CK. The write clocks run at double this speed and DDR takes that up to the effective clock that is quoted and shown by most overclocking software. 

 

Despite what you may hear, GDDR5 isn't actually a QDR memory type, despite the effective clock being 4x that of the CK, it's only DDR. GDDR5X can run as DDR or QDR, but GDDR5 is DDR only. 

Was thinking of chip clock, not CK.  I know DDR4 runs the memory arrays themselves at 400mhz for a data bus speed of 3200 and i was under the impression that the relationship in GDDR5 was 1/4 instead of 1/8.

 

Dont have the time to search up a whitepaper currently, do you know if that is correct?

[Oshino Shinobu]

2 minutes ago, KarathKasun said:

Was thinking of chip clock, not CK.  I know DDR4 runs the memory arrays themselves at 400mhz for a data bus speed of 3200 and i was under the impression that the relationship in GDDR5 was 1/4 instead of 1/8.

 

Dont have the time to search up a whitepaper currently, do you know if that is correct?

Can't say for sure on that. 

 

My understanding is that the command clock is 1/4 of the effective clock (or rather, the effective clock works out as 4x the command clock) that ends up being shown and the effective clock is basically worked out based on the write clock + DDR. 

[Jun Wei Goh]

2 hours ago, KarathKasun said:

GPU-Z is correct and AB is correct.

 

GDDR5 uses a clock quadrupled signaling scheme.  GPUZ is telling you the actual frequency of the memory chips, AB is telling you the clock speed of the memory bus.

 

If you multiply the GPU-Z clocks by 4 you magically arrive at the number that AB is showing.

oh i see thanks man i though i been scammed