Help with o/c e6750

This should be your first stop.
Core2 Overclocking Guide
http://www.tomshardware.co.uk/forum/259899-11-core-overclocking-guide

Next stop should be Shadow's Gigabyte motherboard OC guide:
http://www.tomshardware.co.uk/forum/page-245679_11_0.html
It's for an EP35-DS3L but all the Gigabyte Core2 BIOS's are similar.

Read through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values. Change the System Memory Multiplier from AUTO to 2.00, 2.00B, or 2.00D - whichever you need to set the Memory Frequency to twice the FSB. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 333 MHz, your memory clock should be at 667 MHz.

Now start increasing the FSB frequency.

Download CPU-Z to check your FSB:RAM ratio. It should be a 1:1 ratio.

Warning - confusion factor between what the BIOS calls things and what CPUZ calls things. What the BIOS calls "memory frequency" is actually the memory clock. What CPUZ calls "memory frequency" is half the memory clock - DDR2 RAM, remember? It transfers two chunks of data each bus cycle. What you want in CPUZ is a 1:1 FSB:RAM ratio.

Thank you jsc
I have read the cpu guide already but not the Gigabyte guide so will look at this in more detail but first glance looks like I need to download the latest bios as mine is version f3 and f8 is the latest!
Yes I would like to run the fsb at 400 and keep the ram at 800 as you say at 1:1 the multiplier is fixed at 8x max so will see if I can progress after the bios update
Will let you know what happens
Nick