I currently have 8GB installed (2x4GB) and am wanting to add another single 8GB stick to give me 16GB but the CAS timing on my RAM is 9-9-9-24 and the new one is 10-10-10-27 the make is the same would this be possible to add the single 8GB stick or would this cause issues??

Thanks for any answers

i don't exactly know, I've been looking into this but can't tell for sure that your motherboard will even function if you put in 2x4GB ram sticks in one channel, and an 8GB ram stick in the other. But, by default, your ram will switch the the highest CAS latency timings "10-10-10-27" and speed "ie. 1833Mhz". That wouldn't cause issues by itself, but, the odd channel layout that you have might. So it might be best to just go with a 2x8GB set and replace your old 2x4GB ram set, just to be on the safe side.

Most motherboards these days are dual channel boards, often requiring that you install RAM in sets of 2. My advice is to visit the vendor/manufacturer's web site and see what the specs are for this board. Anything else is a SWAG and will probably leave you with either a non-functional system, or toasty ram. Bear in mind that RAM that has been installed in a system usually cannot be returned for exchange or refund...

Actually, most new motherboards these days are triple or quad channel :)

Dual channel boards don't REQUIRE you to install RAM in pairs, and triple channel boards similarly don't require you to install in three's, and it should still work if you don't. However, the dual or triple channel feature of the board will be disabled then.

So adding 16GB (2 x8GB) should technically work then??

Xyzyxx makes a good point. Some systems do require SIMMs in pairs, but many don't. Again, read the manufacturer's specs. In any case assuming the board supports 8GB sticks, then 2x8GB should work nicely. My board supports 8 sticks, but limits them to 4GB each, with a maximum capacity of 32GB.

BIOS !!! You need new version BIOS on main board!

BIOS versions have many types if that is your problem then you need to know your system specs