Question Confused about RAM speeds

waffl212

Reputable
Jul 8, 2019
55
2
4,535
I'm using a 2x8gb Corsair Vengeance LPX but my ram speed on CPU z only shows 2133 when it's supposedly 2400mhz. On bios there's a drop down where you can see DDR4 - 2133 and so on, and mine is set to auto. Should I put it on 2400mhz manually? If not then why isn't it automatically at 2400mhz.

Also a bit of a related question that might affect the above, is there a way to check if I have the 2400, 2666 or the 3200 version? I don't have the receipt and the box anymore.
 
I'm using a 2x8gb Corsair Vengeance LPX but my ram speed on CPU z only shows 2133 when it's supposedly 2400mhz. On bios there's a drop down where you can see DDR4 - 2133 and so on, and mine is set to auto. Should I put it on 2400mhz manually? If not then why isn't it automatically at 2400mhz.

Also a bit of a related question that might affect the above, is there a way to check if I have the 2400, 2666 or the 3200 version? I don't have the receipt and the box anymore.
Don't know what rest of your system is nut you need to enable XMP/DOCP to 2400.
 

waffl212

Reputable
Jul 8, 2019
55
2
4,535
check the SPD tab, you'll see the available JEDEC timings.
2400Mhz may be preferable to 3200 depending on latency.
CL16@2400 is less true latency then CL22@3200

I've enabled DOCP on BIOS and it set RAM speed to 3200MHz and everything else is on auto. Memory on CPU Z is 1600, JDEC timings are 1066 1066 1066 1600. I'm not sure what Max Bandwidth means, it says DDR4-2132 (1066MHz)
 
1600 is the clock rate, Ram speed is 2x that so 3200 is a sign it's running.

Max Bandwidth may be skewed by what the bios calculates the the best multiplier to be, so that's probably why it scaled to 2133 on Auto.
Just check the CAS # to make sure it's the optimum for your PC.

fractions work fine 16/2400 ~ 20/3000 etc....

P.S. right on the RAM chip there should be a model # on the label.
It can be translated to a speed and CAS value.

I've enabled DOCP on BIOS and it set RAM speed to 3200MHz and everything else is on auto. Memory on CPU Z is 1600, JDEC timings are 1066 1066 1066 1600. I'm not sure what Max Bandwidth means, it says DDR4-2132 (1066MHz)
 
Last edited: