PSU Rattling sound, is it bad?

When playing Skyrim, or other big or demanding games like Mafia 2 or Darksiders 2, my PSU rattles constantly, don't know if it is the fan or the inside. Is it bad? I have the MS-TECH-MS-N750-VAL 750 watt PSU, I have not heard many good things about MS-TECH. I can afford a new one if it is bad. I'm 15 and currently earn 150 euros a month. Any recommendations?

Prolly just the fan.