Custom Built PC Freezes randomly

I got a new custom built gaming PC about a 3 months ago. I was installing Windows 7 when it froze, but I restarted the computer and it worked fine. So ever since then, I have just lived with it pretty much. But about a month ago I took out 1 of the RAM sticks, because my friend suggested that I might have just gotten a bad piece of RAM, and oddly enough it didn't freeze randomly whilst using it, but instead it started freezing when I took it out of sleep mode or sometimes it would blue screen after sleep mode. I just recently put the stick of RAM back in again and it worked perfectly fine for the next 3 days, until today, where it froze twice in one day. Before this, it froze about once a day. This is my first post, and I am not really tech-savy, so just be aware of that whilst typing the response Oh and it might help that I have already done a defragment thingy and a registry cleaning. Also deleted everything in the Temp folder because I read to do that online, and also deleted the stuff in the mini-dump. I have also re-installed Windows twice. Yeah I think that's it please help

So I don't know if it automatically puts my specs in, so I am just gonna do it in case:

Windows 7 Home Premium 64bit
Gigabyte GA-Z97X-GAMING7
EVGA Geforce GTX 700
Intel Core i5 processor
Barracuda 1TB 7,200 RPM SATA 6.0Gb/s 3.5" Internal Hard Drive ST3100005N1A1AS
Ballistix Sport 16GB DDR3-1600 (PC3-12800) CL9 Dual Channel Desktop Memory Kit (Two 8GB Memory Modules)
02G-P4-3765-KR NVIDIA GeForce GTX 760 Superclocked ACX Cooler 2048MB GDDR5 PCIe x16 3.0 Video Card