Welcome to OCN!
The VRMs on the 78LMT will be limited to ~140-150W, and that's with proper air-flow over the VRM heatsink. Assuming a really really nice FX-8320 you'll be power limited to ~4.5ghz on a good day. (This would be pushing the limits of the VRMs and should only be used as a 24/7 OC on this board if you rarely have highly parallel workloads). I highly recommend tucking that fan-wire back away from the VRM heatsink, and mounting one of your push/pull fans on the OUTSIDE of the case so that the turbulent air-pickup for the rad is pulled over the VRM heat-sink. (currently, it looks like your VRM sink is hiding under the side of the fan. This could
Note: Cooling the VRMs is just as important as cooling the CPU to maintain stable clean voltage. When the VRMs overheat instability or thermal protection will kick in (shutdown or low-power-state throttling).
Stable overclocks are not universal. They vary from chip to chip, board to board, and cooling to cooling solution. There are "tolerances" in everything and the difference between stable and not stable can be smaller than the tolerances in the voltage readings, so you'll have to work your way to your own stable overclock.
Setting a higher clock is the easy part of an overclock. Achieving stable efficient overclocks requires first getting a grip on the voltage regulation on your motherboard. Learn how to get stable voltage from the VRMs, then find low voltage stability, THEN work your way up the ladder to a higher clock speed.
Get CPU-Z, HWinfo, and some stress testing software so you can observe voltages and temperatures. Pencil/paper are best to keep track of what you are doing and the results of various testing as you work towards an overclock.
learn how to clear CMOS and be ready for the possibility of having to do this to "fix" a setting too unstable to recover from. Be ready to rest all BIOS settings back to the way the machine needs to work correctly (boot order, time, any particular special capabilities you have enabled or disabled to be compatible with something)
Backup any important data, there's always a minor chance you could corrupt the OS install and have to start over.
- Disable Turbo Core
- Disable APM
- [optional: turn off power saving features like cool-n-quiet, C states, etc]
- [optional: turn of CPU fan control, run full blast while testing]
- Set CPU voltage control to manual, lock in a fixed setting of 1.400V.
- [optional: Set CPU-NB voltage control to manual, lock in a fixed setting of 1.20-1.25V]
- Set RAM speeds conservatively for now (either lower speeds or looser than rated timings)
- Adjust CPU multiplier to 20X (=4ghz).
- With the voltage and clock speed locked to a fixed setting, observe and record CPU voltage regulation from idle to load with every LLC setting the board has (load-line-calibration). If your board is like other GigaByte boards, you'll have a bunch of very ambiguous LLC settings available in an order that makes no sense (Auto, Normal, Low, Medium Extreme, Standard etc). Test them all.
- Select the LLC setting with the narrowest voltage variance from idle to load, and the least amount of voltage variation under load, but still erring on the side of drooping rather than rising when a load is initiated. (a droop from 1.40 to 1.38V would be preferable to a rise from 1.40V to 1.42V when transitioning from idle to load).
- [Note: 4.0GHZ@1.40V will represent a load of ~150W on the VRMs, and will stress the VRMs near the limits. Any chance of overclocking beyond 4.0ghz will depend on finding under-volted stability on your chip, as any clock speed increase will increase power consumption proportionally. Reduced voltage will decrease power logarithmically. Finding the most stable LLC setting at this speed/voltage will also likely be the best LLC setting for your maximum practical overclock]
- Begin under-volting the CPU ~0.025V at a time with the chip still locked at 4.0ghz.
- When it will no longer boot, raise voltage 1 notch (0.00625V) at a time until it will boot and run a short load test with stability.
- Overclock with the CPU multiplier, 100mhz at a time, adding 0.025V per 100mhz. Load test at each step to check on VRM temps, CPU temps (stay below ~60C core temps), and voltage stability (you can check on VRM temps by touch (rough estimate, careful, may burn! direct skin contact @60C for 5 seconds on highly conductive material = 1st degree burn), IR thermometer, or temp probe, max temps at the MOSFETS should not exceed 90C on most motherboards, lower is better for voltage stability, efficiency, and long-term reliability, so the surface of the top of the sink should be quite a bit lower than this. Use good judgement and err on the side of conservative when in doubt. Avoid magic smoke release
Higher voltage and lower temps = stability
Higher voltage causes higher temps (viscous cycle)
Since you will be power limited, every 100mhz over 4ghz will require a cut of ~0.01875V (from the 1.40V starting point) to stay within power limitations of the board. YMMV. (you could use this inverted relationship as a road-map to OC on until you run out of stability then fine tune from there if you want).
After finding a stable overclock that is within the limits of the VRMs and CPU cooling, you can fine tune the overclock for efficiency and performance with offset voltage, low power states enabled, fine tuned RAM speeds/timings, NB overclock, etc.