I think a lot of is just based on what works for the actual board you brought home from the store.
Most people I've seen on boards have stated my our 2.6c should OC pretty well. Mine seems to be stuck at 240 FSB stable, but I haven't attempted to Droop mod or anything, either. I've ruled out RAM issues by testing just my set of PC4000 (didn't have the 2GB kit yet) at 1:1 below it's rated speed and also at 5:4 way underclocked.
Your board may do well with settings and timings set a bit differently than mine - very likely, since you're actually able to get up to 250 FSB with our CPU/mobo combo.
Personally, when I had just the 1GB of PC4000, I had my BIOS settings to:
Under JumperFree Configuration:
Manual CPU External - 240
DRAM - 400 mhz
AGP/PCI - 66.66/33.33
CPU VCore - 1.55
DDR Ref. v - 2.65
AGP v - 1.60
Performance Mode - Standard (might want to test what works best for you - Turbo on or off may impact stability for you at whatever speed you use)
Under Chipset:
DRAM by SPD - Disabled
CAS# - 2.5
RAS# - 3
RAS# to CAS# - 3
DRAM Precharge - 7
DRAM Burst - 4
DRAM Idle Timer - Infinite
DRAM Refresh - 15.6 uSec
Performance Acceleration Mode - Auto (I've tweaked/tested this between Auto and Enabled, too - haven't seen much difference)
Graphices Aperture Size - 128 MB
Spread Spectrum - Disabled
ICH Delayed - Enabled
I then also go into each menu and disable any onboard devices that I don't use - for me, both Serial Ports and the Parallel Port. The Onboard Game/MIDI Port I think was already disabled.
I've also seen suggestions that you set "Legacy USB Support" to Disabled in the USB Configuration section to get more OC, but when I did that, Memtest86 wouldn't recognize my Logitech G11 keyboard running outside of Windows, so i re-enabled it - I suppose Auto wouldn't hurt. Being disabled also didn't seem to give me any more luck getting stable over 240 FSB.
For most of the settings above, you'll mostly have to re-test for yourself. Your original 250 FSB (sig says 3.25) probably was running at the 1:1 DRAM Frequency (400 mhz in the BIOS options) since you seem to have PC4000 RAM (isn't clear if your OCZ is also PC4000, but I'll assume so, since most people try to get RAM that'll run the same speed - circumstances, and poor decision-making, led me to have my mishmash of RAM).
If both sets are PC4000, at that 250 FSB, you were running your RAM right at spec speeds, so the RAM itself wasn't overclocked, and you may have had tighter timings on it than you'd expect if you went over it's rated speed - probably in the 2.5/3/3/7 range or better.
Or maybe you just had SPD timings enabled and didn't manually do any of those timings at all.
Just get your hands dirty again and get in there to see what works for you. I'm far from an expert in this area, but I've tried to catch up lately on "best practices" since I'm trying to pinch just a little more life out of my CPU/Mobo combo. I hope it helps in some small way.
Good luck!
