ChrisM, the G.SKILL Ripjaws memory is a not supported memory since the speed is 2400MHz and the voltage is 1.65V. Even though the motherboard can handle that speed, is the processor who managed the memory and it supports memory speed up to 1600 MHz. The voltage needs to be 1.5.
I was not able to find information on the other memory type you are using.
I recommend you getting a fully compatible memory in order to test the system. You will be able to find all the supported memory configurations and tested memory on the following link. http://www.intel.com/support/motherboards/desktop/dz77ga-70k/sb/CS-033219.htm
Once you get it you can follow these steps
• Check which is the current BIOS version installed on your motherboard. The latest BIOS version is 0066 however there are some users reporting issues with it. So if your system needs a BIOS update please install the previous one (V0064). https://downloadcenter.intel.com/SearchResult.aspx?lang=eng&keyword="Intel+Desktop+Board+DZ77GA-70K"&DownloadType=BIOS
• You can also clear the CMOS removing the battery for about an hour http://www.intel.com/support/motherboards/desktop/sb/CS-028780.htm?wapkw=clear+cmos+battery#datetime
• Test the system out of the chassis, minimal configuration please. (Motherboard, processor, power supply and memory)
- It will be very important to know if you are able to access the BIOS using only one memory stick on DIMM #1, just to find out if the slot is working.
Please try to boot to your operating system and download the Processor Diagnostics Tool and run it on your system using at least one memory stick. At the end it will let you know if your processor “passed” or “fail” the test. This utility is Windows based. Download Center
Remember that Dual channel is enable by default, so this kind of behavior could be related to a defective motherboard or a defective processor.
If you have another processor to test on this board, please give it a try, if not I recommend you to replace the motherboard first.
If the board was purchased less than 30 days ago please contact the place of purchase.
If it was purchased more than 30 days, you can get in touch with our local Warranty Department so they can help you to replace the unit: http://www.intel.com/p/en_US/support/contactsupport
Just in case, remember that low profile memory is not supported by this motherboard. Desktop Boards — System memory information