It isn't. 650 Mhz is the base frequency and 350 Mhz the Idle frequency.
I understand your processor runs at 350 MHz in Graphics based Frequency instead of 650 MHz.
Based on the information from our side, the Graphics based Frequency of the processor model i5-3210m is 650 MHz.
This processor is a mobile version. Due to this, the processor in idle state will decrease the speed for power saving in your system. This is because there are no functions running at that moment and it totally normal and expected.
This situation is expected; however, I suggest you running the Intel® Processor Diagnostics Tool in your system. This application will diagnose the processor components and will report any possible problems with the processor.
You can get the Intel® Processor Diagnostics Tool from the following link:
If running a 64 bit operating system:
If running a 32 bit operating system:
I hope this is helpful for you.