New 7800 Gtx But No O/c

Hi There,

I am new here so please be gentle. I recently built my first PC and had no major hiccups until now having replaced my 6600GT with a 7800GTX.

As you can see from the specs below I built this system with O/C in mind for a bit of fun and to see what I could manage to build myself without buying a generic built system.

The problem I have come against has baffled me but thats not that difficult hence my user name. I have recently installed a xfx 7800gtx with a Danger Den NV-78 block which works fantastically well in it own right but has given me a major (in my eyes) problem.

The bios refuses to complete the boot process reseting everytime unless the fsb is at stock ie 200mhz. I have spoken to gigabyte who cannot help, tried bios upgrades and tried reseating the card but to no avail. However if I put it the old 6600gt this problem disappears.

I can use gigabytes easytune and O/C to 240 fsb but I dont like using software for this purpose.

I apreciate that this may not be enough information but any assistance would be well apppreciated.

I am getting to the stage where I have three options-

1) Help and resolve the problem here (Please)
2) Putting my foot through it (Likely)
3) Buying new asus board or new 7800 (More money)

The system stays pretty cool around 35c and has had no other problems.

Bios version F3 Award Modular

Again thank you in anticipation for all your help.