Standard PSU without fan

PSUs: The source of DC power for all components in the PC & often a big noise source.

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tibbar
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Standard PSU without fan

Post by tibbar » Tue Feb 18, 2003 6:12 am

You may have seen an article on this site that tests whether you can have a normal PSU without a fan, it concludes that you can't as it overheats (with the lid off!).

This is true if you have the PSU in the normal orientation, but if place it on it's back (i.e. power plug underneath it), so that the fan vent is on the floor and the other vent is facing the ceiling, then the heatsinks will actually be able to work the way they were designed! i.e. normally air is sucked in the case and pushed out by the fan - the heat sinks only let convection work if air can pass through their fins in this way.

Obviously this isn't going to work inside a PC. what you need to do is have the PSU externally on it's

So, now I have a machine with the PSU externally (so no heat is dissipated inside the machine) and a quiet Zalman Flower inside.

However, without the psu fan sucking hot air out the case the CPU will quickly overheat on minimum fan setting. So I've added a 92mm case fan where the PSU used to be, also running minimum speed with a zalman speedmate.

PC now runs stable and cool at about 40-45 degrees c, even when throttling the cpu.

ChiefWeasel
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Post by ChiefWeasel » Tue Feb 18, 2003 8:18 am

Hehe, i jus suggested something similar to this in another thread! Are you running it without a fan now? What do you have in the computer? I be v. careful your PSU doesnt overheat, it might take other components with it if it dies! A 5V Panaflo wont create any noise and would improve airflow in the PSU no end. General consensus seems to be that a normal PSU is too crowded and the HSs too small to operate by convection.

tibbar
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will the PSU blow!

Post by tibbar » Wed Feb 19, 2003 4:23 am

hmmm... i've been also worried about this. so far it hasn't and it's been running 24 hours a day constant for 3 days. i've even stressed it out by turning a few dvd's into divx's.

if it keeps working for another week or so (Without burning down the house!!) then i'd say it's safe to do.

best thing is that it is silent (the fan you suggest using is still a little noisy even at lowest speed, i find that all sub 92mm fans tend to rattle a bit at low speed).

tibbar
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psu - surge protector

Post by tibbar » Wed Feb 19, 2003 4:26 am

i suppose i could try and build in a surge protector between the psu and the m/b, i'm not sure if anyones tried this, but at least the m/b won't fry if the psu gives up.

any ideas?

GamingGod
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Post by GamingGod » Wed Feb 19, 2003 6:30 am

I ran an old at power supply fanless for a few months until it died. I thought it was working ok, but after a while I started getting cmos check sum errors everytime I booted and would have to use a bootdisk and reset the bios everytime I loaded. I thought that it might be the cmos battery so I replaced it but it was defantely the power supply, because when I opened it up there was smoke residue coating the entire enside of the power supply, and there were scorch marks on the elctronic board. The power supply was only slightly warm to the touch during this time, so I didnt think anything was wrong with it. Basically im saying, I doubt that you can run a standard power supply with no airflow, at least some type of low airflow is required.

Tore
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Post by Tore » Wed Feb 19, 2003 7:53 am

If I've understood the chimney principle correctly, you need to have colder air at the top than at the bottom for it to give a good draught. The heat from the PSU should be a good start, but I think maybe the difference need to be bigger to get a good enough airflow to cool the PSU. If you build a chimney with the top outside, that might be enough during winter at least :D

ChiefWeasel
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Post by ChiefWeasel » Wed Feb 19, 2003 8:16 am

Found a nice explanation of how chimneys work here.... quite interesting... ok, need to get out more :D

Tore
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Post by Tore » Wed Feb 19, 2003 11:29 am

OK, so you need some height... It's hard to get it more than about two meters inside a normal room. And the chimney need to be isolated to prevent heat loss. The PSU should probably be isolated too, to make sure the heat goes through the chimney rather than just going everywhere.

Hmmm.... Two meter water pipe (22 mm) and isolation is less than $30, and I have a PSU with a noisy coil... Might turn into a little experiment :D

dukla2000
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Post by dukla2000 » Sun Mar 09, 2003 12:48 pm

OK - I am now running my psu (Jou Jye 350W) fanless.

My case is a http://www.chyangfun.com/Product/CF-2029.htm, a version that came with a 120mm hole in the front tin and I carved a matching 120mm hole in the front perspex. So I have an NMB 4710NL-04W-B10-P00 in the front at 7v (my guess blowing 34cfm). At the rear of the case are 2 unpopulated (in my case) 80mm stamped holes, as well as some holes on the case sides and a nice big gap through the psu.

Before I finally pulled a Papst 8412NGL off the front of the psu (a previous mod from it's normal rear mounting, front/rear relative to the PC case) I stuck a thermometer on a psu heatsink and was seeing temps up to about 46C. Now I get temps up to about 50C (idle around 43) - but there is definately warm exhaust air coming out the psu from the front case fan. Maybe the psu is not as cool as desirable for a long life, but it has some electronic whine/hum as well so if it blows will be a good excuse for the next upgrade.

blakerwry
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Post by blakerwry » Sun Mar 09, 2003 10:36 pm

I just wanted to say that the fan on my 1 year old Antec pp303x 300watt PSU died and the PSU ran all day without a running fan... the PSU was barely warm...


The internals of this PSU seem to closely resemble that of the true power 300 watt PSU's... (even though the SL300 is a direct replacement)...

I'm not saying that you can do this yourself... it's just something i noticed... I exchanged the PSU immediately for a SL300...

The PSU was mounted in the top rear of an Enlight 7237 with an 80mm panflo model M below it.. no other case fans.

seishino
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Post by seishino » Tue Mar 11, 2003 9:05 am

I had been thinking of trying to make a convection tunnel from two HDDs, up over a 750 mhz C3, and up through a sideways-imposed 150W PSU. Am I being extremely Naieve in assuming the airflow from such a setup will be enough to cool the PSU to the necessary degree, or should I just give up and throw a fan in?

blakerwry
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Post by blakerwry » Tue Mar 11, 2003 10:50 am

seems like it'd atleast be a good idea to put a slow fan on the PSU

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