What are the chances the RAM will work together?

Solution
It's a 50/50 crapshoot, I work with DRAM on a daily basis, testing and the like and play with different DRAM and combos on client computers. If it was as easy as many want you to believe the manufactures would test and pair up sticks for packaging (which they would do), they would tell you it's fine to add more (especially of the same model, except they don't), they would also guarantee mixing packages of DRAM (which they don't. You also wouldn't be able to skim through the forums and fine hundreds, thousands of thread with members trying to mix DRAM and no joy. On more than one occasion I've gotten matching sets direct from the manufacturers (even consecutive serial numbers) and the packages just won't play. On the other hand, they...
well you will probably hear that it MIGHT not work, or that it is not advisable, but I have never had such an issue, it does really come down to the individual board and system, but I have mixed brands and timings and dates of manufacture with no ill effects. if you are getting the exact same ram it is extremely likely to work, technically I cannot say 100% but if it were to not to, well I think many people would be surprised even if they turn around to say I told you so...

Edit: so go for it.
 

Tradesman1

Legenda in Aeternum
It's a 50/50 crapshoot, I work with DRAM on a daily basis, testing and the like and play with different DRAM and combos on client computers. If it was as easy as many want you to believe the manufactures would test and pair up sticks for packaging (which they would do), they would tell you it's fine to add more (especially of the same model, except they don't), they would also guarantee mixing packages of DRAM (which they don't. You also wouldn't be able to skim through the forums and fine hundreds, thousands of thread with members trying to mix DRAM and no joy. On more than one occasion I've gotten matching sets direct from the manufacturers (even consecutive serial numbers) and the packages just won't play. On the other hand, they might play fine, maybe even in one system and not another. Especially true with old DDR2 and early DDR3 when DRAM primarily stuck strickly to JEDEC specs. See my Fiction article, items 2 and 6:

http://www.tomshardware.com/reviews/ddr-dram-myths,4155.html
 
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