Well, I managed to boot up at 405Mhz after changing some settings that WERE NOT in the frequency/voltage screen. I instantly thought 'woohoo, it's fixed!' went back into BIOS and set 430 and lo and behold it bombs out again. I Just need to find out exactly what it was I changed, that makes this possible.
Any ideas WJA96?
Try the 400MHz strap as suggested by BUFF - it's at the bottom of the memory adjustment screen. Also - I prefer SATA to be [FIXED] and PCIe seems to need to be set over 100 for stability - try 105 or 110. And what's the Northbridge heatsink feeling like? You might need active cooling on it at over 400FSB.
I played about with a lot of settings, but maybe something in the PC Health Status screen is the answer?
It shouldn't be - unless you have the System temperature shutdown switched on or something? What is your CPU temperature? Many E6300's had dished IHSs and needed lapping to run at high speeds reliably.
P.S could someone please give me a brief rundown of PWM and all the settings relating to this board?
PWM is a method controlling motor speeds (in this case a fan motor) by switching the current on and off very fast so that the motor pulses on and off rather runs slowly. Before Intel introduced PWM we only had voltage control which is OK, and it's linear so a fan that runs at 2000RPM at 12V will run at 1000RPM at 6V, but most fans need a minimum of 5V to keep turning over so your actual range of adjustment is 800-2000RPM, because if you drop the voltage below 5V you'll stop the fan, and there is no guarantee you'll get it started again. With PWM you always have the whole 12V applied, but you turn it off an on very fast. I made my own PWM fan controller which would run a fan as low as 100RPM. Also - with PWM you can stop and start the fan reliably.
To use the PWM controller settings, you need a 4-pin fan like the stock Intel HSF. Arctic Cooling, Scythe, Panaflo, Yate-Loon and a few others do PWM fans. If you have a PWM fan then you can set the temperature the fan will kick-in or stop at, and then how fast it ramps up the speed to 100%.