MEMORY SPEED DIFFERENCE, HELP PLEASE..

[pioneerfix]

Hi guys, is it okay have two memory cards with different speed. example with you have one ddr4 4GB that has a speed of 2133MHz  whille the other one is 8gb with 2400MHz speed. I really dont know if my question is correctly phrased, please do help. Im really a newbie on this one. thanks. 

[Yqmxh]

No it is not because the voltage will be different. Don't quote me if I'm wrong, I am almost positive though.

[Jurrunio]

memory sticks, not cards.

 

the faster stick will slow down to match that of the slower stick. Should still work.

 

17 minutes ago, Yqmxh said:

No it is not because the voltage will be different.

the voltages are the same. All DDR4 run at 1.2V, excluding overclocked sticks.

[mariushm]

Both memory sticks will run at same frequency, supported by both memory sticks... 2133 Mhz.

 

Each memory stick has a tiny memory chip  that stores several presets including some "default", "fall back to safety" standard ones. Pretty much all memory sticks MUST include those safe presets, and as far as I remember, the standardized safe presets are for 2133 Mhz and 2400 Mhz maximum.

 

So the 2133 Mhz stick may have Profile 1: 1866 Mhz at CL 12 and voltage 1.2v  , and Profile 2 : 2133 Mhz at CL 14 and voltage 1.2v

The 2400 Mhz may have Profile 1 : 2133 Mhz at CL 11 and voltage 1.2v and Profile 2: 2400 Mhz at CL 14 and voltage 1.2v

 

The bios looks at both and sees that both memory sticks have a 2133 Mhz preset, both run at 1.2v on that frequency, and then it picks the most compatible CL between CL 14 and CL 11, which would be CL 14  (with CL, or latency, lower CL is better, but if the stick doesn't support a low value, there would be errors, so the bios would default to use the higher latency that would be supported by both sticks but may make one of the sticks ever so slightly slower)

 

Some sticks made to run at higher frequencies will need 1.35v to run, like let's say a 2933 Mhz stick... such sticks will run at lower frequencies like 2133 Mhz or 2400 Mhz with lower voltages like 1.2v

 

In theory you can risk running the 2133 Mhz stick at 2400 Mhz and run both stick at 2400 Mhz, but you'll have to be careful enough to use higher values (more relaxed) for some timings to reduce the risk of errors. If the memory stick is made of really bad (or better put ordinary, value, cheap) memory chips, those chips may need slightly higher voltage to be stable and cause no errors at 2400 Mhz... so you may have to raise the voltage to 1.25v for example, from the default of 1.2v