Question PC "crashes" under load

[collinatx05]

I've had my build for quite a while, recently it has been crashing (monitors loose input, sound cuts out after around 5 seconds). I have no idea what is causing this problem, although I have a feeling it is my PSU (A Lepa mx-f1) as the only other thing it could be would be my R9 290, which has had no problems before other than running at (very) high temps under extreme load such as Uniengine or ray tracing Minecraft shaders.

Any suggestions on what it is, and what PSU I should buy? My current CPU is an I5 2500k.

Thanks in advance.

 

[collinatx05]

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