I have a Lenovo Y50-70 with an Intel i7 4710HQ, wich most of the time, i am using it with the lid closed and connected to a 28 inch external monitor. Everything is fine, until i put my computer to sleep. When i resume from sleep, the frequency of the CPU will be stuck at maximum 1800 mhz. If I open the lid just a little bit, to have an image on the laptop monitor, the speed is back to normal, at 2500 mhz. Close it, and again back at beeing stuck at 1800 mhz. I have the same problem on Windows 7 and Windows 8, with every power plan available. Also, i have the same problem, when i disconnect the laptop from the monitor, just to get it in bed with me. While im running on the laptop monitor, the cpu speed is fine but when i get the external monitor connected again, the cpu is stuck at 1800 mhz. The only sollution is to restart the laptop. After that, it will run fine just until i put the computer to sleep or i disconnect the monitor from it and connect it again. So, how can i fix this problem?
Does the processor keeps running at 1800 MHz even when stressing it?
You may try resetting your BIOS configuration back to default or asking Lenovo* to see if there a BIOS update available that includes a fix for this behavior.