Target display mode blinking black

I am having a very annoying issue using target display mode with my iMac connected to my mbp. I have the 2meter thunderbolt cable connecting the two machines. They enter TDM correctly but continually the iMac screen will go black for a second and then reappear. This is very annoying and unacceptable to be honest. I have searched and read many blogs and threads about similar issues, none of which have any answers.

iMac

• 27-inch, Mid 2011
• 3.4 GHz Intel Core i7
• 32 GB 1333 MHz DDR3
• AMD Radeon HD 6970M 1024 MB

MacBook Pro

• Retina, 15-Inch, Early 2013
• 2.4 GHz Intel Core i7
• 16 GB 1600 MHz DDR3
• NVIDIA GeForce GT 650M 1024 MB

Sometimes it seems I will see a message in the system.log around the time this happens:

Aug 8 18:28:35 iMac.local WindowServer[109]: MPAccessSurfaceForDisplayDevice: Set up page flip mode on display 0x042801c0 device: 0x10e074a10 isBackBuffered: 1 numComp: 3 numDisp: 3

If anyone has some ideas on what may fix this issue I would love to hear them.