Tell me about memory

[snubby]

Looking to get some as-yet undecided AMD socket AM3 processor (in my indecision it varies from an Athlon II x2 to a Phenom II x6) and motherboard. I want to have 4GB RAM, but I last built a PC 10 years ago, and it's a little more complex now, so what do I need?

I plan to do minimal overclocking, more likely to do undervolting, does this make any difference? Does the CAS 7-9 make any difference in practice? Is the extra headroom of 1600MHz useful over 1333MHz? Does it make much difference getting 2x2GB now and the same later over stretching to 2x4GB now? Do I need fancy heatsinked DIMMs? And does it make much difference getting matched pairs to either quality or cost?

[PC4Free]

And does it make much difference getting matched pairs to either quality or cost?

I would say always, always get matching RAM - cost-wise its probably cheaper to buy a 2x2GB rather that two modules seperatley

[nibbler]

matching ram and dual channel mode makes a difference. difference between 1333mhz cas9 and 1600mhz cas7 is probably about 3 fps in games (and a lot in bandwidth but as that's synthetic who cares really).

[kalniel]

I plan to do minimal overclocking, more likely to do undervolting, does this make any difference?

If it's stable with less volts then it's fine.

Does the CAS 7-9 make any difference in practice?

Nope.

Is the extra headroom of 1600MHz useful over 1333MHz?

Depends on the supported multipliers - if not overclocking much then no, but you might find 1600 RAM is as cheap as 1333 these days.

Does it make much difference getting 2x2GB now and the same later over stretching to 2x4GB now?

You'll have to run lower timings and/or higher volts for 4 sticks vs 2, but otherwise no.

Do I need fancy heatsinked DIMMs?

Nope. Some tests indicate the ones without heatsinks are better

And does it make much difference getting matched pairs to either quality or cost?

Certainly not in quality - 'matched' pairs often vary more than two unmatched singles. For cost it varies, but often a dual kit is cheaper, not always though.

[Syllopsium]

Unless you're really running utterly performance critical applicatons, the type of memory you run is going to make little real world difference.

Wouldn't bother with 2x4GB if you have at least four memory slots and don't plan to run excessively memory hungry apps.

Heatsinked memory is probably a waste of money, but if the cost of unheatsinked+memory heatsink is less than the heatsinked, you might as well go heatsinked..