MacBook Pro Core i7: Effects of 8GB/4GB with Hard Disk Drive
This page separates out the effect of memory alone when used with the standard Apple-supplied 7200 rpm 500GB hard disk drive.
diglloydSmall benchmark using hard disk drive (HDD)
The diglloydSmall benchmark uses about about 8GB of scratch space in Photoshop CS5. It slightly exceeds the available (usable) memory on an 8GB system by about 2GB.
With 4GB, Photoshop must spend most of its time reading to and writing from the scratch volume.
Here we see that 8GB cuts the runtime by 71% or that 4GB takes 3.5 times longer.
diglloydSmall benchmark using hard disk drive (HDD)
The diglloydMedium benchmark uses about about 16GB of scratch space in Photoshop CS5
With 4GB or 8GB of memory, Photoshop must spend most of its time reading to and writing from the scratch volume. Still, 8GB is far faster than 4GB, as would be expected.
Here we see that 8GB cuts the runtime by 66% or that 4GB takes three times longer.
Conclusions
Having 8GB is hugely beneficial when working with large jobs in Photoshop CS5.
