XW6400 Workstation - RAM upgrade help

Hello, hopefully someone can shed some light on the following problem I'm having.

Product Name: HP xw6400 Workstation
SKU Number: ER236EV
BIOS: v02.38
Operating System: Windows 7 64bit

I bought 8GB (2 x 4GB) of DDR2 PC2-5300F 667Mhz EEC Fully Buffered RAM to upgrade and replace my original 2GB (2 x 1GB) of RAM.

When the new ram is installed (in slots 1 & 3 as per originals) the RAM cooling fan runs flat out at approx 3000rpm continuously. It is far too noisy.

Speed Fan confirms that the new RAM runs approx 20-25 deg Celcius hotter that the original (2GB's) at approx 60-65 deg Celcius. I've confirmed this by installing both the new and old ram at the same time to check..

When I reinstall the original 2GB (2 x 1GB) the fan slows down, RAM temp stays approx 40 deg Celcius and the machine is quiet once again.

My questions are:
Why does my new RAM run as hot without load (no applications running)?
Why does my fan run flat out (obviously because it's hot)?
What can I do to upgrade my RAM without the FAN running flat out and my workstation being to noisy?

Hope all this makes sense, I'm a bit of a novice.