Clinton G.Skill is a fairly large RAM maker and is used by many and the RAM used in a Mac is the same as used in a PC. They use the same hardware.
But the RAM the OP bought is clearly NOT for his model Mac. G.Skill has a Memory finder on there website, just like crucial and kingston. If the OP had used one of those he would not of bought the wrong RAM. But it seems he didn't bother.
To prove that point as to the RAM is the same. when I bought my 13" late 2011 Mac I ordered 8GBs of RAM fro it from Crucial. I returned that Mac and replaced the original RAM in it. I then bought my Dell E6420 and the RAM I had bought for the Mac went into the Dell No problems, as they used the same hardware. I have sionce upgraded the RAM in the Dell to 16GBs and crucial only lists the Dell as taking 8GBs. But I know the Intel chipset will support 16GBs. So I order RAM for the Late 2011 model Mac from crucial, in fact the package says Mac Memory, installed it in the Dell and now have 16GBs in the Dell.
They use the same hardware and take the same RAM. The OP bought RAM for the Newer model Macs and or some generic, Value, RAM that clearly is not the right speed and more then likely is of low quality.