Why use powersupply case?

cheapguy69 · Post by **cheapguy69** » Thu Aug 21, 2003 2:36 pm

I've been curious, if you have a sufficiently cooled (fanned) case, would you be able to create a quiter environment if the power supply wasnt in its own case? Obviously there are voltage dangers, but if the unit was being used for a HTPC environment and rarely opened, the danger is reduced (a bit like CE devices like stereos and such with exposed power supplies). It opens options for passive cooling or the ability of case fans that would cool the air that is inside the entire computer case - without this seperate power supply environment needing its own cooling.

What am I missing from this thought process?

JarsOfFart · Post by **JarsOfFart** » Thu Aug 21, 2003 3:31 pm

In one of the articles on the main site the author takes off the PSU cover and hangs the PSU upside down. This allows the hot air to rise out, instead of being obstructed by the PCB board.

Harry Azol · Post by **Harry Azol** » Thu Aug 21, 2003 4:31 pm

I think the psu cover is needed for EMI shielding..

Post by **Rusty075** » Thu Aug 21, 2003 5:16 pm

The big reasons for leaving the cover on are the possibility of frying yourself on the high voltage elements, and the EMI sheilding.

I think both are overrated

Considering the number of holes manufacturers keep cutting in PSU I don't think EMI is really that big a factor, especially once its enclosed inside another steel box.

DonP · Post by **DonP** » Thu Aug 21, 2003 5:34 pm

I'm just guessing but I think I may have once read that there's an issue with the tunnel effect and cool. I could be talking crap but I think the lid is there to create a tunnel through which the air will flow and will make sure air gets through the components.

As to EMI I think I was saw someone mod their PSU and use a strong wire mesh around it. The holes (diamond shaped holes) were big enough to just about push your fingertip through. I suspect this may be for EMI, but it could always be just a style thing.

DonP.

cheapguy69 · Post by **cheapguy69** » Thu Aug 21, 2003 5:40 pm

Well I can understand tunnel effect, but that would be true for when the PSU was covered in a case. But if you had two case fans in the rear of your case and an exposed PSU (yes there is an electrical hazard, but if it means I can get a quite PSU....) then there should still be sufficient cooling. So that just leaves EMI...

ryan200 · Post by **ryan200** » Thu Aug 21, 2003 7:07 pm

Rusty075 wrote:Considering the number of holes manufacturers keep cutting in PSU I don't think EMI is really that big a factor, especially once its enclosed inside another steel box.

well your not shielding it from the outside your sheilding it against the other peripharels inside your computer case.

to the main guy i would say go for it if your case is well cooled i would, personally i would put a blowhole on the top right above the psu and leave it with the pcb on the bottom but i dont have any fans in the back of my case cause i dont have any new air coming in my case except the side over the processor.

your psu will have less air pressure being forced over its hot spots but if its a good quality psu and it has plenty of watts to spare such as you have a 450 watt psu and only use 200 watts it may not be a problem as far as heat goes most quality psu's will shut off when they get too hot. the main reason a psu has a fan is is cause its atx spec and it was the only out fan back then.

if the emi is to much your computer sould have more problems than normal like memory errors and the such.

i would be interested though how it works out

Post by **Rusty075** » Thu Aug 21, 2003 7:24 pm

ryan200 wrote:well your not shielding it from the outside your sheilding it against the other peripharels inside your computer case.

Actually just the opposite. The PSU doesn't need protection from EMI, it's what is producing the EMI. The cover is to meant to protect both your other components from EMI coming out of the PSU, as well as to prevent it from causing interference with things like monitors, ham radios, speakers, and cell phones, on the outside of the computer.

My point was that EMI must not be that big an issue, since so many PSU's now have 92 or 120mm gaping holes in the bottoms of them, aimed right at the motherboard.

ryan200 wrote:personally i would put a blowhole on the top right above the psu and leave it with the pcb on the bottom but i dont have any fans in the back of my case cause i dont have any new air coming in my case except the side over the processor.

Putting another fan in just to cool the PSU PCB kinda defeats the purpose, doesn't it? Might as well just use a stock PSU then. And ryan I have no idea what you're trying to describe with the rest of that sentence.

ryan200 wrote:your psu will have less air pressure being forced over its hot spots but if its a good quality psu and it has plenty of watts to spare such as you have a 450 watt psu and only use 200 watts it may not be a problem as far as heat goes most quality psu's will shut off when they get too hot.

The power rating of the PSU has no effect on how much heat it will produce. It all depends on how efficient it is at the wattage your system is actually drawing. Some high wattage rating PSU are very inefficient when the draw is low.

ez2remember · Post by **ez2remember** » Thu Aug 21, 2003 11:19 pm

Removing the PSU case actually reduces cooling ability according to this article. Running a PSU without a fan

It seems tunnelling air through a confined area enhances cooling. Having just case airflow may not be as effective, as it provides little spot cooling.

cheapguy69 · Post by **cheapguy69** » Fri Aug 22, 2003 9:04 am

Well the distinction in that article is that they left the powersuppy in the case and just removed the fan.

lenny · Post by **lenny** » Fri Aug 22, 2003 9:59 am

cheapguy69 wrote:Well the distinction in that article is that they left the powersuppy in the case and just removed the fan.

Read the second page of the article.

From the article:

A simple test of this theory was conducted by taking the top cover (with no holes) off.

On the surface of it, the theory seems to be confirmed here, as the temperature jumps 10 degrees in 5 minutes after the cover is removed and climbs all the way to 48C before stabilizing. Putting the cover back on has the even more amazing effect of lowering the temperature dramatically by 10C in 5 minutes.

[/b]

Sigbjørn Lund Olsen · Post by **Sigbjørn Lund Olsen** » Fri Aug 22, 2003 11:57 am

Rusty075 wrote: My point was that EMI must not be that big an issue, since so many PSU's now have 92 or 120mm gaping holes in the bottoms of them, aimed right at the motherboard.

Mmhm, I would imagine it might depend on what you want to do with your PC to start with, i.e. what kind of interference you are willing to tolerate. At least with computers meant for audio editing/recording and such EMI interference can really really play hell with your audio card, especially if you don't have a mammoth budget to get a really expensive and well shielded card (in which case you might as well be buying a mobile studio anyway).

It'd be interesting to see some actual numbers as such, though I imagine that that would be rather expensive?

Cheers,
Sigbjørn L Olsen

larrymoencurly · Post by **larrymoencurly** » Sat Aug 23, 2003 9:39 pm

One of the heatsinks in my Antec reached 70 Celcius when I ran it without the cover, but when I covered it again it stayed below 50C (temporary plastic cover, hole drilled through it for temperature probe), even though Antecs normally run their fans very slowly. OTOH I found a PSU with few openings in its case will make the computer run 2-3C cooler if a lot of holes are drilled in it far from the fan.

larrymoencurly · Post by **larrymoencurly** » Sat Aug 23, 2003 9:46 pm

One of the heatsinks in my Antec reached 70 Celcius when I ran it without the cover, but when I covered it again they stayed below 50C, even though Antec normally run the fans very slowly.