Just noticed something odd about my power supply.

[The Mad Monk]

I've had this system for over three years, and I just noticed this.

The power supply's fan is blowing into the box, not out. I thought they were supposed to always blow out.

Am I confused, did this change sometime during the past decade, or has this computer been running with a reversed-polarity fan for nearly four years?

It's a PIII 450 mid-tower with a 500 watt supply, and the supply is positioned almost right over the chip (which has it's own fan and huge heat sink), so the majority of the air flow is going across it. The air coming out of the supply isn't exactly cool, but it's not really warm, either.

The labeling on the supply, in its present location, is upside down.

[Urban Ranger]

The fan should blow out.

What the heck are you doing with a 500W power supply? Or rather, is it really a 500W power supply?

BTW, how many fans does the power supply have and how are they facing?

[Mr. Harley]

It's hard to put a power supply upside down, if you look at it, the bolts are NOT laid out symetrically. They do normally blow out. Maybe somebody installed the fan in backwards. You could unplug and then pull the power supply and open it, voiding any warranties remaining. Carefully, because while it's unplugged, it still has capacitors and can shock you, just remove the mounting screws and reverse the fan, replacing the mounting screws. But if you aren't having any problems, then don't fix it is my motto.

[Fve Crathva]

The PS fan should definitely blow out--for obvious reasons--but older PSes' blew in, I assume because that way you were guaranteed a draft over the processor heatsink.

SP

[notyoueither]

Thank the geniuses at Intel. That was their original ATX spec. It should have another fan blowing hot air into the system from the bottom of the PS. Yes, that's right, blowing hot air into the system.

[Dis]

I wouldn't think it would be the end of the world if it blew in. You would still get air circulation. Just maybe not as good.

The biggest reason for the fan not to blow in is because of dust. Without a filter you will bring in tons of dust.

For people overclocking their computers they should have fans blowing in and out. For fans blowing in, they recommend you use filters to prevent too much dust from getting inside your case.

But dust isn't the end of the world. I live in the desert. And I never dust my house . The inside of my computer will just build up massive amounts of dust. I try to blow some out, but usually not that often. I even accumulate large dust balls inside my computer

edit: oh I thought you meant a case fan, not a power supply fan . Well in any case, if your chip hasn't burned up yet- you should be okay .

[notyoueither]

I think I have a few dead rodents inside mine. Maybe even a small dog.

[Urban Ranger]

Some ATX power supplies do have a fan right over top of the CPU blowing down, but not all of them do. In fact, only the expensive units have them.

[The Mad Monk]

I got the wattage by multiplying the input voltage (100-125) and amperage (5) listed on the label. Google listings say it's actually 145 watts.

It's a LITEON PS-5151-6B. It just has the one fan that I can see.

Since it has been doing fine for so many years, I don't see me changing it -- I am wondering if this could do with the two hard drive failures and one CDROM failure I've had during that time.

edit: dammit, the 145 watts is on the label, I just didn't see it. Bah.

[The Mad Monk]

Originally posted by notyoueither
Thank the geniuses at Intel. That was their original ATX spec. It should have another fan blowing hot air into the system from the bottom of the PS. Yes, that's right, blowing hot air into the system.

That bottom fan is the one I'm noticing. If there's a second fan behind the vent in the back, it's not apparent.

Of course, it's not in a good position for me to see it.

[Urban Ranger]

145W?

Run to your nearest hardware store and get yourself at least a 250W power supply.

[notyoueither]

The original Intel spec did not last too long, for obvious reasons. First they stopped putting two fans in, and then some bright light got the idea of venting the hot air out of the system. Like they used to do. It was a breakthrough.

[The Mad Monk]

The inside of the case is extremely dusty -- I thought it was just because I don't dust much, either.

Perhaps I should put some gauze over the PS vent?

[Urban Ranger]

No.

Buy a new power supply. If you get a 350W or 400W, you can use that in your next computer, too.

[Dis]

I have a couple of open slots in the back of my comptuer where I used to have cards and such. dust gets into my case either way