stupid question - the psu fan is supposed to point down into a desktop yes?

[yoda313]

I finally bought and installed a new powersupply for my quadcore pc. It came with an old dell one and was getting loud and warm, two no-no's of course.

So I bought a thermaltake 600 watt psu and got it all set up and running.

However it didn't really specify whether or not the fan was supposed to point down into the case or not.

This may sound really stupid but the only other way for it to point is up to the top of the case.

So the fan is supposed to point down into the case right?

Thanks.

Edit - (everything is running just fine right now with it pointing down by the way, though it's a little noisy but that just might be the quality of the brand and nothing I did).

edit 2 - it's a tower desktop forgot to mention with the psu at the top of the unit.

[zing269]

It doesn't matter which way it is oriented as long as it isn't obstructed.

[yoda313]

It doesn't matter which way it is oriented as long as it isn't obstructed.

Ok. Thanks.

[aedipuss]

mostly depends on the case, mine has openings to the outside where the psu is mounted so the fan draws air from outside the case and exhausts hot air out the back.

[yoda313]

mostly depends on the case, mine has openings to the outside where the psu is mounted so the fan draws air from outside the case and exhausts hot air out the back.

Mine is a dell optiplex 755:



The output where you plug it in is exposed to the air so that is where the outflow goes I'm assuming.

[aedipuss]

yep hot air goes out the back where the plug is. the other opening in the psu is the air inlet.

[yoda313]

Ok I think I'm good than. Thanks.

I'm still learning things so thanks.

[johns0]

You can tell which way the psu should be mounted because the screw holes are in a certain pattern,you can only install it one way.

[yoda313]

You can tell which way the psu should be mounted because the screw holes are in a certain pattern,you can only install it one way.

Oh than I guess I really am all set since it's screwed in securely.

[DarrellS]

There are a lot of variables which dictate how you mount the fan. The fan on socket 478 CPUs sucked the heat away from the cpu and blew the hot air out of the side of the case through a horn. Socket 775 CPUs are set up stupid (trying to suck air towards the cpu) which is why you need to use an after market cooler like the Cooler Master Hyper 212. These fans should face toward the back (although I have seen them facing towards the top if there is an outlet on top). I would not use a stock cooler on any modern boards.

My case uses a PSU on the bottom where the fan sucks air into the PSU and out the back of the case. I have five 120mm fans. One in the front to blow air over my HDDs, one on my Hyper 212 to blow air towards the back, one in the back to get the heat out the back, one on top to get the heat out (heat rises) and one on the side to blow cool air on the graphics card and MB.

Then there is liquid cooling which is another option with different opinions on how to set them up.

EDIT: My bad. I thought you said CPU fan. The reason a top mount PSU is not a good idea is that you are moving hot air though the PSU which will shorten it's life span (heat is your enemy). Since I switched to a bottom mount PSU, I haven't had to replace the PSU. Before, I was constantly having to replace the PSU.

[johns0]

Your post has nothing to do with the psu mounting.

[DarrellS]

...and I'm surprised that you were able to install an after market PSU in a Dell case. I tried a few months back and the new PSU didn't work so I had to buy a new case (and a MB for a better CPU that I had since the Dell I was replacing was a piece of crap). I ran into the same problem years ago with an HP. It used a proprietary PSU and HP did not make a more powerful PSU which I needed to run my graphics card so I ended up doing my first build. I haven't bought a factory PC since.

IMO, the case is the foundation of any build. One with cooling in mind. I ended up modifying the case that I bought for the HP board, cutting a hole in the top to get heat out and one in the side to get cool air in. All I use nowadays is the Cooler Master 690 II Advanced. It is a mid tower that is built better than most full tower cases with cooling in mind. It has two fan mounts on the bottom of the case (one is for the bottom mount PSU), two on the top, two in the front, one in the back and two on the door. It has one on the right side but you have to use a thin fan since there isn't room for a regular 120mm fan. It also has an adapter to mount a small fan to cool the graphics card/s. The Cooler Master case is built with liquid cooling in mind but works great with my Hyper 212 CPU cooler and sells for under $100.

[yoda313]

@darrells - I will say this that the dell case has this little metal protrusion that the factory psu is supposed to slide into to lock into place. My replacement is floating on top of that slightly. So its not fimrly in place. I mean its screwed in and all but its not a 100% flush.

I may get around to trying to snip that off somehow.

[hello_hello]

Going by the pic you posted, the Dell is BTX, not ATX, hence the side of the case on which the MB mounts is opposite to the side it'd mount in a "traditional" ATX case. Dell was one of the few manufacturers that adopted the BTX form factor. It was ignored to a certain extent and never really caught on. Like ATX it was a form factor introduced by Intel, but they stopped making BTX motherboards years ago.

A BTX motherboard couldn't be mounted in an ATX case unless it was specifically designed to take both types, although I'm pretty sure BTX and ATX power supplies are interchangeable. Dell might have had their PSU's especially designed to "lock-in" in some way, unless that was a difference between BTX and ATX PSUs. I'm not sure.

Dell (and other manufacturers) often used to use a proprietary "form factors" so you couldn't use standard "off the shelf" replacement parts. Therese days, I think Dell mostly stick to the standard form factors.

BTX was designed for better cooling because the airflow was more efficient. That's why your PC doesn't have a traditional CPU fan. The BTX design was for "straight through" airflow where a fan on the front of the case blew air directly over the CPU and then it was exhausted out the rear (maybe with the aid of a second fan). Some designs seem to mount the front fan closer to the CPU rather than on the front of the case, but the principle is the same. I assume that'd generally happen when the front of the case isn't directly open to the air, but the BTX design was effectively to have a CPU cooling "wind tunnel".
http://www.nix.ru/art/pic/faq/cases/Gateway_btx_stor.jpg
http://img.tomshardware.com/de/2006/07/04/vergleichstest-intel-viiv-pc-computer/dell-inside1big.jpg

I think one of the reasons BTX didn't quite catch on was due to the fact it was designed to fix the cooling problem caused by the high operating temperature of P4s, but once they went away it was to a certain extent a fix for a problem which no longer existed.
Even many of the current ATX cases seem like that to me these days.... with so many vents for 120mm fans there's barely any case left..... you'd really need to be a serious overclocker to need something like that. Or maybe run an AMD CPU. Admittedly 120mm fans can move a lot more air than smaller fans so they can rotate slower which cuts down on the noise, but generally one in the front and one in the rear would be more than enough.

As you've discovered you can't mount a PSU in a case the wrong way because the screw holes are aligned in order to stop you from doing so.
Back in the early days, the PSU fan often did two jobs. It'd keep the PSU cool while keeping air flowing through the case. That's why they were top mounted, because heat rises. PSU's often still perform the same dual cooling function in budget or small form factor PCs today.
Moving the PSU to the bottom might in theory extend it's life as that way it's drawing in cool air and only cooling itself, independently of the air in the case. I do tend to wonder if that's another fix for a problem which didn't exist though. The capacitors in PSUs are rated to work at pretty high temperatures, even warm air would probably keep them cool enough. I've owned quite a few PCs over the years and they've all had top mounting PSUs. I've only ever had one PSU fail, and that was due to a known design fault.

[yoda313]

Thanks hello hello that was very informative. FYI it was a atx PSU that I put in.

Sent from my Nexus 7 using Tapatalk

[DarrellS]

Yeah, I was thinking the Dell computer that I worked on didn't have a CPU fan which would explain why it burned up. All it had If I remember correctly was a plastic tunnel to supposedly force the air out the back. Like I said, this Dell was a piece of crap. It's sitting on the kitchen floor because it wasn't worth trying to fix. Since I already had a good dual core cpu laying around and the new PSU that didn't work in the Dell, I bought a case, a Gigabyte G41MT-S2PT MB with onboard graphics and a Hyper212 cooler. That should last my brother for a while since he doesn't do much more than browsing the internet.