Pairing different DDR3 sizes?

[Isbiten]

Sitting at 4GB Ram atm.
XMS3 2x2GB 1600MHz 9-9-9-24 (Are these sticks good enough for OC?)
i5 750 @stock (planning to OC to 4GHz)
Corsair TX750
P55A-UD3
GTX 260 < going to be a 7950

Incoming 7950 and with this I wanna play games like BF3 which I read benefits from more than 4GB RAM.

Now, are there any cons to getting for example 2x4GB (of the same RAM) and pair it with my existing 2x2GB?
I'm planning to get the exact same type of RAM.

I'm going for either 2x4GB or 2x8GB

 

[Blain]

Now, are there any cons to getting for example 2x4GB (of the same RAM) and pair it with my existing 2x2GB?
I'm planning to get the exact same type of RAM.

Populating your DIMM slots with larger modules usually leads to the least opportunity for conflicts (problems).
Having said that...
If you are planning on keeping your current 2x2GB DIMMs, you should match them with the same Speed, Voltage, CAS and Brand if at all possible.
This is not to say different memory will not work with your current DIMMs, just that you reduce the risk of incompatibility if the new memory is an exact match of your current RAM.


If I were in your shoes, I'd get an 8GB kit and buy This Mushkin 996988 kit, based on my memory evaluation criteria...

If I were shopping for high quality memory, I would use the following parameters as a guide...

* DDR3 rated at 1.5v or lower
* DDR3 rated at the lowest CAS I could afford
* DDR3 rated at the highest clock speed I could afford
* Limit the scope of my purchease to G.Skill, Mushkin, Corsair XMS or Crucial (non-Ballistix)

While not wavering on the voltage point, I would balance the other issues with my budget.

Remember, my goal is not pure "benchmarking" performance, but simply finding the highest quality memory I can afford. ^_^

The only reason I pay a premium for low latency, high speed, low voltage memory is...
Quality and quality alone.

1.5v is the JEDEC DDR3 voltage standard.
Stay with 1.5v or less if you can afford it..

 

[Isbiten]

Populating your DIMM slots with larger modules usually leads to the least opportunity for conflicts (problems).
Having said that...
If you are planning on keeping your current 2x2GB DIMMs, you should match them with the same Speed, Voltage, CAS and Brand if at all possible.

That's the plan.
Buying the exact same model/brand with exact same specs, just bigger.

 

[BonzaiDuck]

That's the plan.
Buying the exact same model/brand with exact same specs, just bigger.

Ditto on all of it. I've used different RAM-kit models of the same manufacture, because they overlapped perfectly in speed, voltage and timings.

But if he can find the same model of RAM in a 2x2 or 2x4GB kit, that's "one of the best" ways to go. Even so, RAM is so cheap now, he could almost get a 16GB 2x8GB kit and set the old kit aside as a set of known, working "test" RAMs.

 

[Charlie98]

I would just swap out the old RAM for the new 8GB set and call it a day. Unless you are doing something besides gaming that requires a bucketload of RAM, I prefer to keep it simple. Even encoding video and things like that, I don't think I've ever gone over 4GB of RAM useage.

 

[nk215]

I would match voltage first (if you can't match everything). You may not get the full speed of your ram but that wouldn't show up in actual user experience. I mismatched my ram all the time and no ill effect ever come from that. Just make sure to set the speed manually, if in doubt, to the slowest of your ram.

 

[tweakboy]

Any stick is good enough for a OC. Its weather they can handle the higher voltage to attain higher bandwidth.. gl

I wouldn't I thought DDR3 was one size ? hmm