Voltage and timing questions

[Jase77]

Hi, I'm wanting to add some more memory to my system using an MSI P55-GD85 motherboard. It's a dual channel memory motherboard and the 4gb pair I originally bought for the system is no longer available. This 8gb set seems to be the most comparable however I noticed it's listed running at a different voltage. 1.5V versus the 1.65V of the original set. Is that going to have any impact on performance? Or does that not matter at all? I don't usually mess with memory voltage and timing and don't know too much about it.

And my second question is about the timings. They're both supposed to run at the same timings (7-7-7-24). However, when I installed the original set I just assumed it would run at the listed timing specs and didn't even bother checking it when I installed it. But when I made the decision to add more RAM, I went back and checked the timings for my original set and was surprised to see it was running at 9-9-9-24. I can modify the timings in the bios. Do I just go in and manually do that or is there a particular reason why it's not running at the timings it's listed for? Thanks for any help!

 

[alyoshka]

Default Mobo Voltage to RAM modules is 1.5V thus the earlier RAM was automatically supplied that voltage and thus works slower @9-9-9-24. If you increase the DRAM Voltage to 1.65 you will get the old RAM to function @7-7-7-24, but, do not mix those 2 RAM modules although they will run fine since both seem to be running @9-9-9-24 at 1.5V, it is still not advisable.
Of course that is, if ,you were to buy memory with the 9-9-9-24 timings @1.5V.....
Just buy the new set and keep that alone in the board. That would still be an upgrade and will allow for future increases in the RAM.

 

[alyoshka]

Actually sell the old modules off and get 2 sets of these new RAMs, then they'll all be fine and great together.

 

[Jase77]

Thanks for the earlier reply. I got busy and never responded or got around to upgrading but I did actually have a follow-up question. I agree it sounds like it'll be better to just buy two of the 8GB sticks. However, my motherboard manual states, "Due to the chipset resource deployment, the system density will only be detected up to 15+GB (not full 16GB) when each DIMM is installed with a 4GB memory module."

While I'm fine being able to only use 15 of the 16GB of memory as it's fairly cheap, will this motherboard limitation cause any performance or other issues if I decide to add in the full 16GB? Would I be better off just sticking with 8GB? The cost of the sticks is not an issue and I'd prefer to just get the full 16GB even if I can only make use of 15GB worth of it. Thanks!