Combine DRAM G.Skill TridentX 4xmodules with different size 2x4 / 2x8

[l.pirwitz]

Hi there,

i have some questions about the RAM. I just combined these two packages.
https://www.gskill.com/en/product/f3-2400c10d-16gtx
https://www.gskill.com/en/product/f3-2400c10d-8gtx

The 2x4gb module was bought in 2015 and the 2x8gb module these days.
Both are nearly identicaly, except the size of course.
They should have PC-19200 but CPU-Z shows me in the spd-tab that the 2x4gb modules have PC-12800 and the 2x8gb just PC-10700.

Timings for both modules are.
10-12-12
tRAS 31
tRC43

I also put on the XMP Profile in my ASUS Z97 Pro Gramer, bought in 2015 and CPU Z shows me in the memory tab a DRAM-Freq of 1199.8 MHz .


But if im looking in the bios dram status it shows me 1600Mmhz for the old modules and 1333mhz. This status window is left handed and on the left topside there is an info box showing a CPU freq and so on and there the dram frequencie is 2400 mhz which comes from the XMP Profile.

Im wondering now if everything is ok or if missed something ? Could you help please and tell me if something is wrong or so ?

thank you very much.

 

[feelinfroggy777]

Mixing and matching RAM does not always work the way you think so. Even if you match the exact same models. The chips on the RAM could have different memory manufacturers as well. CPU Z is showing 1188.8 because of double data rate (DDR). You multiply that number by 2 to get the DDR speed. SO CPU Z is showing it running at 2400mhz. The Bios is probably confused because you have different sizes and speed rated RAM installed.

But honestly, there are not a lot of applications that require more than 16gb of RAM. There are no games on the market that require more than 16gb of RAM either. The other 8gb of RAM will not make your system any faster as it will just sit there idle doing nothing. In fact, running 4 sticks in a dual channel board will just put more stress on the memory controller in the CPU. So unless you have specific applications that can use the extra RAM, I would just sell the 2x4gb kit.

 

[Snipergod87]

Mixing and matching RAM does not always work the way you think so. Even if you match the exact same models. The chips on the RAM could have different memory manufacturers as well. CPU Z is showing 1188.8 because of double data rate (DDR). You multiply that number by 2 to get the DDR speed. SO CPU Z is showing it running at 2400mhz. The Bios is probably confused because you have different sizes and speed rated RAM installed.

But honestly, there are not a lot of applications that require more than 16gb of RAM. There are no games on the market that require more than 16gb of RAM either. The other 8gb of RAM will not make your system any faster as it will just sit there idle doing nothing. In fact, running 4 sticks in a dual channel board will just put more stress on the memory controller in the CPU. So unless you have specific applications that can use the extra RAM, I would just sell the 2x4gb kit.

Those sticks are not running at 2400 that would be like a 75% or more overclock. Its running at 1200Mhz

 

[feelinfroggy777]

Mixing and matching RAM does not always work the way you think so. Even if you match the exact same models. The chips on the RAM could have different memory manufacturers as well. CPU Z is showing 1188.8 because of double data rate (DDR). You multiply that number by 2 to get the DDR speed. SO CPU Z is showing it running at 2400mhz. The Bios is probably confused because you have different sizes and speed rated RAM installed.

But honestly, there are not a lot of applications that require more than 16gb of RAM. There are no games on the market that require more than 16gb of RAM either. The other 8gb of RAM will not make your system any faster as it will just sit there idle doing nothing. In fact, running 4 sticks in a dual channel board will just put more stress on the memory controller in the CPU. So unless you have specific applications that can use the extra RAM, I would just sell the 2x4gb kit.

Those sticks are not running at 2400 that would be like a 75% or more overclock. Its running at 1200Mhz

I don't know about that, both of those RAM kits support speeds of 2400mhz if you look at the specifications. If he enabled XMP, then in theory they should be running at 2400mhz. But when you mix RAM everything goes out the window. One of the RAM native speed is 1600 while the other is 1333. So the bios is showing the native speeds. I don't know why it would down clock both kits of RAM to 1200mhz when both of them natively support higher speeds.

Additionally, do a quick google search "cpu z double data rate speeds" and you will get a million hits saying exactly what I said at the beginning.

https://www.reddit.com/r/Amd/comments/62el4s/does_cpuz_only_show_dram_at_half_their_memory/

http://www.tomshardware.com/answers/id-1962423/ram-speed-cpu-accurate.html

http://www.overclock.net/forum/18051-memory/1346124-cpu-z-shows-ram-half-speed.html

 

[Snipergod87]

Mis read his RAM info as PC3-12800 and PC3-10700 not PC3 19200
Its running at 1200Mhz which signifies 2400 cause it is dual pumped.

 

[l.pirwitz]

Thank you very much for your answers.

I just installed the modules yesterday and tested in the evening some Games like RocketLeague,LoL, FarCry5 and also my Flight Sims X-Plane 11 & Prepar3dV4.

So for now everything works with the mixed Modules. But i think the best Solution is the one you descriped, but i wont sell the modules. I will save them and maybee i can build another computer with these modules.

For the CPUZ Infos, i know that i have to double the shown DRAM Freq. I was just a little bit confused by all these different numbers shown in the BIOS and CPUZ and wanted to find out which of these numbers are the correct one.

best regards & again thank you very much for your help.