Read Write speed requirement for D600 from Nikon?

Does anybody know exactly what the Read Write speed requirement for the D600 SDHC Memory card is?? I have just purchased and used a Polaroid 16GB rated at "35MB/s - Class 10& UHS-1 rating and I think I have some issues with it with wierd reading writing , power up/down , focusing issues which I think is related to the card being used. I actually tested my new cards at 10.5 MB/s Writing and Reading at about 15MB/sec which is reasonable for a class 10 card right?.  BTW I used a program from Steel bytes to test the card - be very careful for it will destroy whatever data on the card during the test - make sure you are backed up. also I did not test the whole card memory maybe the first minute of its content? Come to think of it, I should have tested both cards all the way to the end of 16MB ---approx 20-25 minutes though. The issue did not presented it self until after 100-150 exposures?? I will not have my new D600 until Wednesday because the "old" one is on its way back to B&H not because of any camera issue - but they I had to rebuy with the new Kit deal with the 24-85mm lens for the same price plus a new Oben monopod - what a deal.

Also the camera came with a Sandisk Extreme 16GB - I had no issues with that - I did not get a chance to test that one though (its packed to go back as well).

See tophee's thread on this issue with my reply :http://forums.dpreview.com/forums/post/50479656