rams of different sizes- bad or not?

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[princee18]

I want to know:would mixing the size of different ram chips be bad?

All chips would be the same speed and voltage.
Example: 1gb,1gb,2gb, and 1gb = 5gb total?

Or, how about an odd number: 1gb x3?
please give your comments on this.

[Xtreview]

Mixing the memory is not a good idea due to:
1) memory performance , single channel instead of dual channel .
2) some compatibility issue (witch some motherboards)
3) lower overclock capability since motherboard with less memory slot overclock better ,

[rajsharma_85]

Most RAM is now dual channel meaning the machine pumps the data through 2 channels at a time. If one channel only accepts .25gb, that's all the other channel will take as well. Plus the RAM needs to be the same frequency.

[surfville]

Its is a bad idea. I think better put in two identical rams with same frequency and ram space. that way it wouldn't get to many compatibility issues in your motherboard.

[sox7000]

3) lower overclock capability since motherboard with less memory slot overclock better ,

Nnd why this is happening? 

[Xtreview]

3) lower overclock capability since motherboard with less memory slot overclock better ,

Nnd why this is happening? 

Due to the extra load placed on the memory controller and chipset in order to coordinate with more than 2 slots .