New Computer Build keeps crashing/freezing

[FloppyCanFly]

Hi guys I was on a budget for this build so for the first time ever I decided to go with AMD. And boy has it been a struggle so far. The performance has been very inconsistent. My issuse is that it's constantly freezing and crashing or operating slow or fast on different boots.

 

Sometimes it will crash/freeze randomly on when I open a few programs at the same time requiring a hard reset. Sometimes it will freeze out of the blue on a game after performing very well.

 

My specs:

 

FX 6300 

GIGABYTE GA-78LMT-USB3

240GB Samsung SSD

500w 80+ Thermaltake PSU

2 x 4 8GB Crucial Ballistix Sport

EVGA GTX 750 TI

An old DVD ROM drive (plan on taking it out)

 

This isn't my first build but the installation has just been a complete nightmare.

 

- I didn't realize that my motherboard was on the older side. I see a bunch of random code and numbers when posting instead of the familiar gigabyte logo. (any fix to that?)

- Posting is slow and often just freezes or doesn't recognize the boot device

- Sometimes the it makes it past the post and freezes on the windows loading screen, other times it does a full boot in under 13 seconds 

- It will work fine and then I'll go to the bathroom or away from the computer for like 5-10 mins and it I'll come back to find that it crashed while it was idling on desktop

 

What I've tried so far:

 

- memtest with both sticks in and no errors (I should prob swap one out)

- windows diagnostic again no errors

- safemode boot (seems to work with no issues)

- Installed video drivers off disc (not from website yet)

- Bios looks up to date

 

Any and all help will be appreciated. I built this for my cousin and I have no idea how to help him ;L