Laptop Memory: 533 Mhz @ CAS 4 or 667 Mhz @ CAS 5?

[ColdCaller]

I just purchased an Inspiron E1505 from Dell on a great SlickDeal (http://www.slickdeals.net/#p7215) and it is shipping with 512MB of Single Channel RAM, 533 Mhz @ CAS 4. The FSB of this computer supports 667 Mhz, and 667 Mhz 200-pin SODIMMs (PC2 5300) only come in CAS 5 for the time being. CAS 4 is the fastest it gets, however (which is a testament to how slow laptop memory really is).

So, what would be better for my system? 2x512MB @ 533 Mhz, CAS 4 or 2x512MB @ 667 Mhz, CAS 5. Both would obviously run in a Dual Channel setup.

Thanks.

[Terry]

I'm far from expert on this but my understanding from overclocking adventures is that best efficiency is gained by matching memory frequency with FSB and then relaxing or tightening memory timings for stability.

[Lifthanger]

I don't think the difference would be groundbreaking.
It could be that both settings perform almost the same, but 667MHz at CAS 5 should be a tad faster. But it should also drain more power from the battery.
Would you need to buy 2 new modules to run 667?
Personally I'd keep it at 533MHz, because the impact on performance would be too slow, while increasing the heat output and decreasing battery life.
But I've never overclocked a laptop before. [img]/images/graemlins/smile.gif[/img]

[ColdCaller]

Yeah, I would need to buy two new modules, whereas with the 533 Mhz I can just buy another matching stick of the same density to enable dual channel mode.