RAM vs SSD?

[ritmomundo]

I've read that having an SSD in the macbook air negates the need for more RAM. Its my understanding that RAM allows for faster access to program info than accessing a spin-up HDD, because RAM has always been sorta like flash memory. And any extra memory required above and beyond the capacity of the RAM goes to the HDD. So if you have an SSD that pretty much can be accessed as quickly as the RAM, then it shouldn't make much difference whether you've got 2GB or 4GB. Is this correct?

 

[HiddenGem]

The RAM (Random Access Memory) is faster for quick access. I guess if the SSD was superfast you might be able to get away with less ram or it would be less noticable. I'm no expert on this though.

 

[simsaladimbamba]

RAM is much, much, much, much faster than even a fast SSD, as DDR3 RAM can have read and write speeds of 6GB/s and faster (17GB/s), SSD are around 200MB/s, therefore more RAM allows you to have more applications and documents open, without RAM being copied to the SSD, which is quite fast with an SSD, but RAM is still faster.
Btw, "memory" is not the same as "hard drive capacity":
What is Computer Memory? RAM vs Hard Drive
RAM vs. Hard Disk

 

[Hellhammer]

RAM is still much faster than SSD. 1066MHz DDR3 has latency of 0.9375ns while Intel G2 X25-M SSDs (couldn't find info about the Toshibas) have latency of 65-85 microseconds (65-85 000ns). SSDs can deliver up to 285MB/s while 1066MHz DDR3 in dual-channel mode can deliver up to 17.1GB/s (17 100MB/s).

Sure, SSD does speed things up a lot because it's so much faster than a regular HD. However, it is still not as fast as RAM so if you know that you will be running RAM intensive apps, then don't hesitate to go for 4GB.

 

[ritmomundo]

Thanks everyone for the responses. It makes more sense now.