New PSU and my comp randomly shuts off -- please help a new builder

Hi all,

I'm going for a silent build and a just installed my Seasonic 400w Fanless PSU.

First few hours worked great.

Then I leave for the bathroom and come back and the computer is mysterious turned off. I click the on button again and it boots for 5 seconds and then fails.

I've been assured by many that 400w is plenty for my i5-4670k and GTX 660 (no OCing, no SLI).

Should I RMA it? It's soooo crappy when you have to this with a PSU. I wonder if I can keep all the cables routed and just swap the PSUs. (yay for modular).

Also, if my comp randomly turns off, do I need to run some software diagnosis?
9 answers Last reply Best Answer
More about psu comp randomly shuts builder
  1. My comp is now back and up in running. I smeleld the PSU and no hint of smoke or anything.

    Should I RMA it? Should I not be running my comp right now? It would be tough not too...only device with internet in my house.
  2. You need to step up to at least 600w PSU .You don't have enough power.
  3. 380 is too close to the max. You need a little headroom - especially with a fan-less.
  4. SR-71 Blackbird said:
    You need to step up to at least 600w PSU .You don't have enough power.

    Blackbird, you were the very person in the other thread of mine that said it would work, no problem at all. I can up the wattage, I guess.
  5. I missread your other post , should be higher , I thought that Fanless was a 500w.I apologize.
  6. I've checked on other forums --

    I've also done "wattage calculators" online. Everything says 380w is enough.
  7. Can some other ppl weigh in on this?

    Is it a defective unit or not enough wattage?
  8. Best answer
    380 is very close to the max. Max does not mean sustained output - ratings decrease as temps increase. I like to double any power supply requirements I need - whether it is an electronic circuit I design or computer I build.
    Edit - overkill yes - problems - NO.
    Just think if you had to put out max effort - I think you would get very hot and then your output would go down. Can you monitor your psu temps?
    BTW I am an electronic technologist - last 30 years.
    You have to look at the derating curves for your psu to get a good grasp of how much wattage will be needed.
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