Mixing same type of ram but different sizes

Hi guys, i would like to fill all 4 lanes of my mobo but i dont want/need another 16gb of ram, could i buy a 8gb kit of the same brand,speed and type and use it without any issues?

 

i have a 16 and 8 gig kits running happily together

 

Yep, that will be fine. You can mix different types as well, the ram will just run at the speed of the slowest stick.

 

Thanks for the quick responses guys, ordering new ram now

 

if the sticks have different chips on them there is a slim chance they wont work together but most sticks work fine together

 

The only issue you may run into is if the board cannot address all the banks, what motherboard do you have?

 

I ended up deciding to order another 16gb just in case it didnt work lol

But i have a new problem now, the board im getting is an asus gryphon z97 which only supports up to 1866mhz, the ram ive ordered is 2400, is this going to be a big problem? I dont mind the ram running at 1866 but it feels like a waste of money

 

you can possibly overclock the ram or just run it at the lower speed and notice no difference whatsoever.

 

Just purchased a 16gb (2x8gb) set to add to my current 8gb (2x4gb) and its working. Both are 1600Mhz, albeit with different timings (which shouldn't make a difference I guess)

However, according to CPU-z (SPD tab) it says the 16gb set is running at 667, whilst the 8gb is at 1600; whilst in the memory tab its at 800mhz which is correct (at the slower timings of the 16gb though).

I did set in BIOS to XMP (Asus P8z68v pro) which auto set the RAM to 1600. Didn't change a thing though.

Ultimately not a big issue, but ideally would like all RAM to be at same frequency.

Any suggestions?

 

the memory tab in cpu-z is the speed that all the sticks are running
the spd tab is there rated speed not what there at
if your running 1600c11 that is a fairly large performance hit to the cpu similar to 1333c9 in programs that overflow the cpu cache

 

Ok, understood.

Thats the thing, the 16gb kit is rated to be 1600 (according to the packaging and its model number, which is CML16GX3M2A1600C10). yet in SPD its states it max bandwidth as PC3-10700 (667MHz)

The 16gb kit is c10, whilst the 8gb is c9. I presume that both kits would be then run at c10 timings as a result.

I'll try running just the 16gb kit, and see if its correctly identified as PC3-12800 (800MHz).

 

Something doesn't sound right with that kit almost like it has been falsely re-branded or a dodgy Chinese clone:
http://www.corsair.com/en/vengeance-low-profile-16gb-dual-channel-ddr3-memory-kit-cml16gx3m2a1600c10

With the latencies you may want to manually set the timings if you start getting issues to the C10 (looser) as sometimes the SPD can have conflict issues and system won't boot.

You won't need to just run the one kit - instead in CPU-z select the "slot" drop down menu and select each module and you will get the data for the different kits displaying.

Click to view full size!

Here are my two different kits SPD's:

Click to view full size!

It can be noted the kit on the left is PC3-12800H series whereas the kit on the right is the series before PC3-12800.

The JEDEC tables are different:
- PC3-12800H
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 7.0-7-7-22-29 @ 622 MHz
JEDEC #2 8.0-8-8-25-33 @ 711 MHz
JEDEC #3 9.0-9-9-28-37 @ 800 MHz

- PC3-12800
JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency
JEDEC #1 6.0-6-6-16-22 @ 457 MHz
JEDEC #2 7.0-7-7-19-26 @ 533 MHz
JEDEC #3 8.0-8-8-22-30 @ 609 MHz
JEDEC #4 9.0-9-9-24-33 @ 685 MHz
JEDEC #5 10.0-10-10-27-37 @ 761 MHz
JEDEC #6 11.0-11-11-28-39 @ 800 MHz

 

I guess its possible. If so, will need to take it back to the store.

I've manually set it to C10 timings, specifically 10-10-10-27
It has for some reason changed the command rate to 3T, whereas I believe it should be 2T.

Done, here are the pics.
This is the Corsair 16gb on its own, in the primary channels. I took out the 8gb kit in case there was some kind of conflict. But as you can see, it still states 'max bandwitdth' as PC3-10700(667MHz)

Click to view full size!

This pic has both 16gb and 8gb installed.

Click to view full size!

Oh and currently running the latest BIOS 3603 that was released back in 2012.

 

Send the shop that screenshot and pose the question:

Why is the RAM Kit (CML16GX3M2A1600C10) showing a max bandwidth of PC310700 (667MHz) when the technical specifications of the product clearly note - Speed Rating PC3-12800 (1600MHz)?

See how they respond.

Either way the kit is running at 801.0 MHz.

 

Thanks, did what you suggested.

True indeed.

 

thats normal its the jedec speed which is the max most sticks will run till you load xmp
the xmp is 1600 10-10-10 which is what its rated for and should run fine
all normal