The problem is most likely in BIOS settings. High speed ram will usually default to 1366mhz, or as you have noticed half of that 683 reported. Easiest way to get setting correct is to download cpuz and look at speed tab, it will show you all reported settings for XMP profiles (overclocked ram). Use the CAS timings listed as well. This will OC your FSB as well so make sure your cpu settings are readjusted to avoid BSOD unless it can handle it. Some motherboards cant run the ram higher than 1600 so don't be disappointed if that's the case.
Thanks for the reply. I went into the BIOS, but I could only find options to overclock it. It is not my motherboard because it was running fine and when I installed my graphics card, the speed went down to 532mhz. I noticed this because the boot times took way longer.