According to your spec sheet:
http://ark.intel.com/products/75047/
You're given ram isn't bad at all. However, the i5-4670 can play well with "ddr3-1600". So, all things equal any memory with this speed with the lowest cas latency would be best (at the best price available). Just double check when you find such ram if it's on your mobo's compatibility sheet or not (go to manufacturer's website and find pdf file for ex). Just because it's not on there doesn't mean it won't work but it's extra peace of mind before finding out the other way. Your 1333 ram should be fine but technically it won't be "best". I have patriot 1333mhz ram and have a great oc but it probably could be better with 1600 ram but I just went with $ value as I...