I have 1600MHz ram but it shows up as 716MHz in Speccy

Speccy shows the real clock speed of your RAM (716Mhz).

Since it's double data rate (DDR) RAM the effective clock speed would be 1432Mhz (716x2).

You have 1600Mhz so there is either some system overhead using that missing 168Mhz or you need to fine tune your voltages or motherboard settings.

I don't know if you bought the ram at newegg or not, I'm just using this link as an example:
CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMZ8GX3M2A1600C9 - Newegg.com

In my humble opinion, I don't think there is any humanly possible way to tell the difference of 168Mhz, maybe if you're gaming there would be a problem with the frames per second (fps), but you won't know until you try.

As far as checking the actual speed you did that when you used Speecy. There are other hardware information gatherer programs out there you could try, but the best I've seen are the ones a local computer shop would have, its a small device that the tech would plug your ram into and it would give a read out on all the specs of the ram being tested.

But, this may be a moot point because I double checked the memory support list for your motherboard and I came up with a discrepancy. That is the reason it took me so long to reply.

You posted the model number of the ram you installed as, CMZ8GX3M2A1600C9, and according to the qualified vendors list it should be either:
CORSAIR 4GB CML16GX3M4X1600C8 or CORSAIR 4GB CMZ16GX3M4X1600C9,

You can double check me at: http://download.gigabyte.us/FileList...-z77x-ud3h.pdf

Scroll down a bit until you reach DDR3 1600 listed at the upper left corner, the list for 1600 starts at page 4 on my reader and the ram I'm thinking you need is at the bottom of page 5.

I hope I'm wrong.

Unless you are using them to run an integrated GPU, that tiny discrepancy is irrelevant.
Heck only benchmarks can detect the difference between 1333 and 1600 RAM for CPU performance, go figure detecting 150 mhz.