Laptop RAM - Quantity or speed?

[wevcore]

Hello,

I've just salvaged some RAM from my old laptop and put it in my new laptop.

Before I did this, CPU-Z said I had 4GB @ 800Hz. Now it's saying 6GB @ 655Hz.

Will my laptop perform better with less, but faster RAM, or more but slower RAM?

I use my laptop for the internet and engineering simulation / analysis software.

Thanks in advance!

Kevin