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Such thing as too large a PSU?

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October 18, 2002 8:51:22 PM

Is there any harm to be done getting a power supply that is more than enough Watts?

I am trying to put together a rig with a high end CPU, 4 HDD RAID array, water cooling, and peltier. I want to get a power supply that is enough to handle all this. To be safe can I get a 430 or 500 Watt power supply?

More about : thing large psu

October 18, 2002 9:30:27 PM

Psu's provide wattage, which is voltage times current. Components suck current off the psu. Since voltages are more or less constant in a computer, the wattage consumed by your system is a matter of how much current your system wants to suck. The psu does not force itself on the system. An overpowered psu will do no damage, it just has power to spare.

John A
October 19, 2002 5:08:07 AM

Yeah.

If anything, it will run cooler and longer.

But it is very possible to pay too much for a psu. There is crap, then there's quality, then there's exotic.

[Jedi mind trick] You LOVE Palladium. [/mind trick]
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October 19, 2002 6:22:12 AM

As already said, it can't cause harm.

The current any device draws depends entirely on its electrical resistance. Even if your PSU could supply a megawatt, the system would only draw what it needs.

To use a crap analogy... A McDonalds restaurant may produce 10,000 burgers a day, but you will only take what you can eat :smile:
October 19, 2002 6:47:18 AM

Thanks guys.
October 19, 2002 7:23:21 AM

looks like the smartest thing to do is going for a big one, or you might end up a bit short in a few months when upgrading the toys

<font color=red>Got a silent setup, now I can hear myself thinking.... great silence</font color=red>
October 19, 2002 6:35:16 PM

I agree. If you upgrade often then It is better to get a higher Wattage PSU.
October 22, 2002 2:47:52 AM

Ditto! Smartest thing i did was get the monster 550W enermax PSU. Consumes no more than a standard PSU (infact probably a little less as it's more efficient and doesnt put out as much heat)
Its got ample power to spare, the voltage rails are stable and sweet, has handled all the overclocking i threw at it and it runs cool and quiet.

<b>And if you gaze for long into Toms Hardware Forums, The Forum gazes also into you! :eek:  </b>
October 23, 2002 6:43:40 AM

A few odd supplies on the surplus market won't work right at all if the load is too small, a case in point being the 300W Delta DPS 300BB (Delta may be the largest maker of PC supplies), which won't start with some slow Celeron or Socket 7 CPUs, even if the +3.3V is loaded with a resistor.

I'd rather have a quality supply rated for enough power than a higher rated supply of unknown quality because many of the latter are poorly designed, not only lacking good short circuit protection but often prone to oscillation or generating big voltage spikes that can destroy its own components.
October 23, 2002 6:07:25 PM

Yes, most switching mode power supply topologies cannot provide an output that meets spec unless they are loaded. It is common pratice to design the minimum load as 10% of the maximum rated. Most switchmode powersupplies has an internal 'power good' monitor that prevents the PSU from starting up unless it is sufficiently loaded.
October 24, 2002 2:56:19 AM

Now thats interesting.
How does that explain how some powersupplies can be 'turned on' with a simple wire connecting 2 plugs of the motherboard connector cable with no other devices in it.
Ive seen that done with a cheapie psu and a expensive enermax. (The PSU's were left on & used to display various casefans and noise outputs, so essentially their load was a couple of watts at best.)

<b>And if you gaze for long into Toms Hardware Forums, The Forum gazes also into you! :eek:  </b>
October 24, 2002 5:54:20 AM

Well, then its probably not 'most' PSUs that need loading, but some. Anyway I have seen it on several, however, they were all of the pre-P4 (extra 12V connector) type.
Perhaps the designers has found a better way to do it.

<i><b>I dont need a sig!</b></i>
June 7, 2009 2:06:00 PM

hammerhead said:
As already said, it can't cause harm.

The current any device draws depends entirely on its electrical resistance. Even if your PSU could supply a megawatt, the system would only draw what it needs.

To use a crap analogy... A McDonalds restaurant may produce 10,000 burgers a day, but you will only take what you can eat :smile:



I don't know about that mcDonalds things... a couple of buddies of mine will sometimes each walk out with 15-20 burgers apiece. They love 39 cent hamburger day.
August 3, 2009 10:48:18 PM

ARGON said:
Is there any harm to be done getting a power supply that is more than enough Watts?

I am trying to put together a rig with a high end CPU, 4 HDD RAID array, water cooling, and peltier. I want to get a power supply that is enough to handle all this. To be safe can I get a 430 or 500 Watt power supply?

dude you want something more like a 600 or 700 watt for that biuld mabye more
!