Adding new memory - Advice for unpaired Corsair memory sticks

[kajimshanti]

Goodday dear community,
I have this problem:

I bought a rig built by a guy 1 year ago. It has an Asrock z77 extreme6 mobo and 12 gb of corsair RAM (8+4) on single channels. Now it's time for upgrades and I wanted to add some memory to reach about 20-24 gb.

I wanted to simply add memory of the same type so that I could take advantage of dual channels.
My problem is that when I looked into my pc specs, I found out that my memory sticks are "lonely specimens" that were originally part of two kits (a 2x4 and a 2x8 kit). Now to find the right soul mates for my lonely sticks is surely a tough task (since everyone of course only sell the whole kit. Btw I live in italy were it's not too easy to bump into good deals regarding pc components).

For reference, my sticks are:

Half of this kit: CMZ8GX3M2A1600C8 ( http://www.corsair.com/en/vengeance-8gb-dual-channel-ddr3-memory-kit-cmz8gx3m2a1600c8 )

And half of this one: CML16GX3M2A1600C10 ( http://www.corsair.com/en/vengeance-low-profile-16gb-dual-channel-ddr3-memory-kit-cml16gx3m2a1600c10 )


Since I can't find other unpaired memories like mine (and likely cannot sell mine at good price either), would you consider advisable pairing them in dual channel with these two?

CMZ4GX3M1A1600C9B ( http://www.corsair.com/en/vengeance-16gb-single-module-ddr3-memory-kit-cmz4gx3m1a1600c9 )

CML8GX3M1A1600C10 ( http://www.corsair.com/en/vengeancer-low-profile-8gb-ddr3-memory-kit-cml8gx3m1a1600c10 )

The specs for the 8gb sticks appear to be exactly the same, but for the 4 gb sticks they have slightly different tested latency. However I'm no expert in pairing memories and I don't know if plain looking at the specs is enough to be safe.

If you think that I'd better not to pair them this way, now that you know of my situation: what would you advice to solve my issue in the most cost-effective way?

Thank you all for the support

 

[Mr Kagouris]

If this is a gaming machine you won't need more than 16GB, so just ditch the 4GB stick and add a second 8GB stick identical to yours.

 

[kajimshanti]

If this is a gaming machine you won't need more than 16GB, so just ditch the 4GB stick and add a second 8GB stick identical to yours.

I mainly need to do 3d modelling and photo editing inside VMs (with pci passthrough)

 

[Mr Kagouris]

I honestly cannot recommend mixing RAM capacities and chips (anything you buy now will not be the same chips that are in your RAM), especially in applications where reliability is required. I can only recommend that you sell your current sticks and buy a full 4x8GB kit.

 

[kajimshanti]

Ouch...thats gonna hurt... So you reckon that the CML8GX3M1A1600C10 and my half-kit CML16GX3M2A1600C10 have different chips and should not be mixed? Or can I at least save a bit by keeping my 8gb stick and mixing it with a CML8GX3M1A1600C10 and another full CML16GX3M2A1600C10 kit? Besides, I don't think I need as much as 32 gb, the rest of my hardware is not that top-notch... You say I should only aim either to 16 or 32 gb, no in-betweens?

 

[Mr Kagouris]

No in-betweens, and no mixing old with new sticks (or different capacities). Mixed RAM is too unreliable for workstation standards.

 

[kajimshanti]

OK. So, let's say I forget about dual channel and take a single 16gb stick to replace my 4gb stick... is that gonna be bad too? And what about my current set up (8 + 4 on single channels), is it unstable?

 

[Mr Kagouris]

Mixing RAM capacities isn't the best of ideas but since they're most likely from the same chip batch and the same frequency it's unlikely you'll see any issues with those. And yes, replacing just your 4GB stick would also be bad because you'd still have the 8GB stick with different chips and a different capacity. Also, you can't use 16GB sticks (divide the max supported RAM of the mobo with the number of slots to get the max capacity per stick).

Unless you're willing to risk losing work because of RAM errors or the sticks plain not working together with no defective sticks, only go with 2x8GB or 4x8GB.