I doubt that it is outputting at 27 dBm. You have probably just maxed out the power. It is just like running your car engine at 10,000 RPM, when it was designed for 6,000 RPM. It can do it, but not for long before it blows up.
If large files are crashing your card, then it is likely overheating. You should probably get your replacement card on order right away.