Hi sunofwisdom You are a little premature in determining your throttling is caused by a MB malfunction. Hold off that RMA for the time being.

You need to conduct a series of stress tests to determine if throttling is caused by heat to both CPU or your VRMs. (common causes)
If the VRMs are hot to touch, try having a desktop fan blowing on them. You may have to provide extra fans for this purpose if the desktop fan helps.
As you have windows power saving features off, we can discount that as this would only throttle down at idle if enabled.
During the stress test you should monitor temps using HWMonitor or CoreTemp. Not both, Just one monitoring application at a time to avoid erroneous readings.
Your cooler should be OK for stock values but may be inadequate at higher frequencies.
It would be a good idea to log these figures in case your system is shutting down under load.
What changes and settings do you have or have made in Bios as this is another issue?

Quote from another forum and relevant.

C1E Support drops your voltage when the cpu is below 5% use.

CPU TM Function (better known as CPU Thermal Management) is the setting that will throttle or even shut down your computer when your cpu temp (not the core temp, this is important to note since a cpu temp is about 10-15*C lower than the core temp) exceeds 100*C.

Intel SpeedStep Tech is the setting that will lower your multiplier to reduce core speed and heat.

Intel C-State Tech as far as i know has to do with low level sleep functions and is only used in a server situation, for this i maybe incorrect so please let me know if i am.

None of these settings at a stock cpu speed will cause any lag or issues at all, if they did they would not have been put on the cpu. however, in an overclocking situation were stable voltage is needed to be clean and consistent you would want to turn off C1E, SpeedStep and C-State as all of these change the cpu's resources. CPU TM Function can stay on if you want to have that extra security knowing that if your cpu fan dies then your computer will shut down, though also note that if a cpu actually reached 100*C on the CPU which would be about 110-120*C on the core damage would likely be done to the cpu even before the computer has a chance to shut down.

MM