0708 (assuming you have a B3 board). The BIOS the B3 boards shipped with was garbage.
Everyone so far has reported a slightly higher OC's or the same OC at lower voltage after updating from 0404. Plus the update allows you to enable PLL, and lets you see SPD for each installed DIMM from the BIOS.
The major thing to note about this board is that there is no way to directly set the vcore.
Vcore appears to be determined from a combination of your chips native VID, the value and sign of the CPU Offset Voltage, and the Additional Turbo Voltage (ATV) setting under the CPU Power Management Menu.
Another thing to note that is it's extremely common for the OC protection to kick in (you will boot to a screen that says "Overclocking Failed! Press F1 to enter setup") even when your OC is fine, especially at higher OCs (I started experiencing it around 4.7GHz). If you see this screen without having first had a bunch of failed boots, go ahead and hit F1 and then just hit F10 and enter to save and continue with the current settings. The PC will boot without reporting a failed OC. Mine was doing this every time, but now that I've settled in at 4.8GHz I never see that screen.
So my advice is as follows:
1. You MUST use manual settings for BOTH CPU offset and ATV (in the CPU Power Management menu). Leaving either of these on auto led to my board giving 1.50v for the same OC that is stable at 1.376v, which is obviously terrible.
2. Changes to the CPU offset do NOT lead to a corresponding change in vcore under load as you would expect--it's usually close, but never seems to be precise. Working with the ATV setting is much
easier. While it remains possible that there is some fundamental difference between these settings, I haven't found it.
3. The choice of whether to use LLC is a complicated one, but in general I would recommend leaving it off. Enabling LLC will actually *add* voltage (as much as 0.1v!!!) under load, and the amount of voltage added is dependent on the degree of load. So for example, turning on LLC I saw voltage increase by 0.072 under IBT, and then when I upgraded to SP1 and the AVX binaries it went up 0.032v more. Note that if you want to enable LLC you *can* set the Offset Sign to - to reduce the voltage under load. However, at ~1.42v I was unable to get into windows at 4.8GHz with LLC enabled, but am rock solid with LLC disabled and around the same voltage (although it mostly droops to 1.392v).
Step-by-step advice for OCing this board is as follows:
Ai Overclock Tuner: MANUAL
BCLK Freqency: 100 (for now)
Memory Frequency: Manually set to stock for your DIMMs (I'll leave you to play with this once you like your CPU OC)
Internal PLL: Enabled (but note that one user had trouble OCing his RAM with this enabled)
OC Tuner: DO NOT USE
EPU Power Saving Mode: Disabled
Turbo Ratio: start at stock, increase gradually as you work on your OC
DRAM Timing Control: Manually set to stock for your DIMMs
CPU Power Management:
CPU Ratio: Auto
Enhanced Intel SpeedStep Technology: Enabled
Turbo Mode: Enabled
Turbo Ratio: same as in the main Ai Tweaker menu
Additional Turbo Voltage (ATV): start at 0.004, increase by 0.008 as necessary to achieve stability as you OC. If you decide at some point to Enable LLC, you will need to decrease this (or your Offset) setting by approximately 0.08v to keep the same voltage.
All other settings leave on Auto
Offset Mode Sign: +
CPU Offset Voltage: 0.005
DRAM Voltage: 1.500v (or w/e is stock for your DIMMs)
VCCIO Voltage: 1.05v (increase if OCing your RAM)
PCH Voltage: 1.05v (increasing may help you increase BCLK, use the color coding to determine what's safe).
Load-Line Calibration: Disabled (but see discussion above)
CPU Spread Spectrum: Disabled
Once you boot from these settings at stock, open CPU-Z and run IBT or Prime-95 or w/e. Note the vcore CPU-Z reports under load. From here on out, whenever you increase the ATV by some amount, your vcore under load will also increase by that amount (your vcore at idle will not change, and you won't need it to).
From here, start increasing your multiplier and increase ATV to achieve stability as necessary, staying within whatever voltage ranges you're comfortable with. I see no reason why 1.4v is problematic if your temps are under control, and even 1.45v and more should be ok, although with the AVX libraries your temps will be extraordinarily high. Both the 2500k and 2600k have a max VID of 1.52v.
Once you achieve your maximum stable multiplier at 100 BCLK, there are two more thing you can do to improve your OC.
1. Go up to the next multiplier and decrease your BCLK by 0.2 until you can get it stable. Once you find that, you can increase the multi yet further--it's up to you and benchmarking where the sweet spot is.
2. The other thing you can do is take max stable multi and *increase* the BCLK by 0.2 until you become unstable. You can also try decreasing your multi and increasing BCLK further. Again, it's up to you where you think your sweet spot is--also keep in mind that higher BCLK will also produce higher RAM speeds at a constant multiplier (although a lower BCLK may also allow a higher multiplier...).
OCing results on this board from OCN members (feel free to add yours!!!):
Pro OCing Results[/ame]
Link to edit spreadsheet: https://spreadsheets.google.com/ccc?key=0Aqo3fzVwb52YdFMzMDNadHhYLWpZZFVNd1dZMVNYdVE&hl=en&authkey=CJq1lrAL#gid=0
P.S. I *am* responsive to PM's if this page needs updating!