What if PSU is too small

[MeDownYou]

What happens you you boot up your machine with a powersupply that is too small?

 

not that i'm going to do this, but i'm curious

[zlolslavez]

It will either not turn on, or randomly shut down when you are using too much power.

[Enderman]

it would work fine

but if you put it under load (like playing games or running benchmarks) it would crash

[dmanschramm]

When your machine draws too much power, it will cause errors and shut down spontaneously. It could damage parts. Don't do it. Always overestimate your power consumption.

@MeDownYou

[airdeano]

on boot, pretty much nothing as the load is nominal. but under load it would

shut down due to lack of power requirements to run the devices properly.

[gilm0re3]

Pretty good forum post on the subject from anandtech: http://forums.anandtech.com/showthread.php?t=2034132

[MeDownYou]

dang you guys are fast...

 

Nice to know too

[gilm0re3]

When your machine draws too much power, it will cause errors and shut down spontaneously. It could damage parts. Don't do it. Always overestimate your power consumption.

@MeDownYou

However, the likeliness of damaging parts is fairly minimal, since any decent power supply should come with short circuit protection. Data corruption is probably a lot more of an issue, especially if the storage drive was right in the middle of a write.

[zlolslavez]

Keep in mind over estimate means +100 on pcpartpicker, or typically what ever the card reccomends. Over estimate does not mean, oh, 430 watts usage, better buy Corsair AX 1500I.

[othertomperson]

Worst case scenario, it could get excessively hot and become a fire hazard.

[Dimwitted]

The other thing is "underpowered". Not all watts are the same. A high quality "underpowered" unit is far superior to a cheap "acceptable" power unit. Read the reviews that JonnyGURU does. All those tests mean something. Power stability is far more important than pure output. That's why it pays to put up the money for a quality unit and why people put such faith in things like Japanese caps. Component quality and circuit topology play an important part in why one psu is better than another.

 

So if you have a Seasonic based 550W unit vs a cheap 750W unit and your gpu says you need a 600W unit, I wouldn't worry and keep the 550W. It'll do you better in the long run than the cheap unit ever could.

[the pokemon kid]

The PSU will catch fire and then rip a hole in the space time continuum and life as we know it will be over... Please refrain from testing this...

 

In reality, it would allow you to boot, but as soon as the system tries to draw more power than the PSU can supply the system will shut off.