System won't post when memory frequency changed

I have a P4 2.8 on an Asus P4S8X-X mobo. FSB is 133 as standard with 21x multiplier.

Have taken it FSB to 147 = 3.07 ghz all cool and stable but memory is running synchronus with FSB. Any faster and I start to have problems - temps OK but 3D Mark 2003 falls over.

I think the processor should go quicker and that memory is perhaps the problem. The bios gives me the option to set the memory 75%, 100%, 125% or 150% of FSB. Have tried to lower memory frequency to 75% but the system won't post on this. (Memory = PC2700 - 333mhz)

Any ideas how to lower the memory frequency from 1:1 and still get the PC to start!

What type of memory? It might be tapped out.

ELIXIR 512 DDR-333MHZ CL2.5 PC2700

Part no is M251264D58HB2G-6K

Wannoc, your reply go me thinking and I checked the manufacturers site at the link

http://www.elixir-memory.com/products/file/M2U51264DS8HB2G-R1.0-0318.pdf

The spec states that it will run at speeds of up to 166mhz. That being the case I assume there will be no problems with the memory running synchronous with FSB of less than 166mhz?

Can anyone confirm that - if so I can rule memory out as the cause of problems above 147 mhz FSB.