Installing more RAM

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Hi all, I recently bought another Kingston DDR3 1600Mhz HyperX 8GB KHX1600C9D3K2/8GX - 2 x 4GB RAM to add to the 8GB I already have installed. It is exactly the same as the RAM I have already so there shouldn't be any compatibility issues right? Well, when I install the extra 8GB my system won't boot. The fans spin for a couple of seconds, then stop, then spin again, then stop and so on and so on. There is no POST beep from the speaker either. I have tried resetting the CMOS and the same thing happens again. When I take out the new 8GB the system boots fine again. Is this just a case of faulty RAM or could there be another cause? In case you need to know my system specs are;

MOBO - Gigabyte GA-Z77-DS3H
CPU - Intel Core i5-3570K
H/S - Cooler Master Hyper Evo
RAM - Kingston HyperX DDR3 1600MHz CL9 8GB (2x4GB)
HDD - Seagate Barracuda 1TB 3.5" SATA-III 7200RPM 64MB Cache
GPU - Gigabyte AMD Radeon HD 7870 2GB
PSU - Cooler Master GX Lite 700w
OS - Microsoft Windows 7 Home Premium 64GB

Thanks for reading

 

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Thanks for the answers. I tried the new RAM on its own in the sockets my old RAM was in and it worked fine. I then put my 2 old RAM sticks in the 2 extra empty sockets and now all 16GB works I'm pretty new to the whole PC building and upgrading thing so I have no idea why it wouldn't work before but its all good now. Thanks again for the help guys