Is it safe to run the PSU fan at 5volt?

jpsa · Post by **jpsa** » Sat Apr 10, 2004 9:18 am

I have a chieftech 360w psu I thing it only uses about 250w, is it save to conect its original fan to 5volt? would it get enough cooling?

yermolovd · Post by **yermolovd** » Sat Apr 10, 2004 9:29 am

Im running Enermax 300W @ 5V Panaflo, since january i think, all good so far..

Gooserider · Post by **Gooserider** » Sat Apr 10, 2004 11:37 am

Qualified maybe... It depends on your exact setup, how your case airflow works, etc.
Only thing to do is try it, while monitoring your temps for both the CPU / system and the PSU. If either gets to high, you'll need to go to a higher voltage.

Key things to look at are whether or not there is a good alternative air path out of the case, (good) or does the PSU also function as the primary case exhaust? (bad)?
How hot is the air coming out of the PSU before modification? If it's cool, you can likely get away with it. If it is already pretty warm you probably won't.

Gooserider

Jan Kivar · Post by **Jan Kivar** » Mon Apr 12, 2004 12:47 am

5V would be completely safe, if the PSU gets fresh [read: cool/ambient] air. If the PSU sucks in pre-heated air from inside the case, You might end up in troubles. Gooserider presented few good things to consider/try.

Maybe You should build a PSU duct?

Cheers,

Jan

tino · Post by **tino** » Mon Apr 12, 2004 1:02 am

I think it might rely on whether you get a good sample of a psu. I've been running my Q-tech psu at 5.5v on a Zalman fanmate for about a year without problems so far, and my 'other' fan is a 92mm Papst running at 5v.

For much of this time I fooled around with overclocking, and had a 9500 pro, and it managed OK. Realised now that this might be a little dangerous, and run an Athlon at 1.1v, and a mx200, so I feel a little better with so little power draw.

My next psu buy will be an external brick, once a reliable and efficeint model gets released.

ez2remember · Post by **ez2remember** » Mon Apr 12, 2004 5:40 am

I have the same Chieftec 360W PSU running with a Panaflo 80 L1a @ 5v. The fan is mounted outside of the PSU and has been reversed. The fan is no longer tight against the internal components of the PSU, thus improving airflow and less air turbulance.

The air coming out is cooler than when I had the PSU mounted inside the case with a Panaflo @ 7v. I have been running it for about 6 months now and @7v inside the case for 1yr+. I think iits pretty safe... Even if it packs up one day, it was time to get a new higher efficiency PSU which would be modded in the same way.

Its whisper quiet (inaudible) at all times no matter the load.

Update: Specs - P4 1.8A @ OC 2.4Ghz, Radeon 9500, 512DDR, 60GB DM+9

trodas · Post by **trodas** » Mon Apr 12, 2004 6:16 am

Using Enermax 431W with both fans w/o grils and hardwired to 5V for more that year. Now on Baron 2500+ in Epox mobo, Vcore 1.9 and FX5600XT 305/610Mhz and no problem so far.
Fanless watercooling, fanless case and the air going out is barely warm.

So, my answer is yes.

croddie · Post by **croddie** » Mon Apr 12, 2004 6:38 am

Isn't it dangerous to have the PSU out of the case? I thought containing sort of PSU radiation is a main function of a case.

sthayashi · Post by **sthayashi** » Mon Apr 12, 2004 6:52 am

croddie wrote:Isn't it dangerous to have the PSU out of the case? I thought containing sort of PSU radiation is a main function of a case.

You mean like a metal enclosure around the PSU? Sort of like what's there already?

MikeC has been working with his external PSU computer for some time without any immediate short term problems. Of course, whether or not it's affected his ability to have children, we won't know for a while.

silvervarg · Post by **silvervarg** » Mon Apr 12, 2004 7:37 am

The biggest danger is that is can easilly fall down and hit your foot with a sharp corner. Perhaps the wires going into the computer is short enough to stop the fall, but then the yank in those cables is not what you really want.

The radiation that comes out from the PSU is probably less than 1/100 of what your cellphone puts out. You do get some magnetic field from the transformer in the PSU. Though it is probably a lot lower than what you get from your cellphone charger.

ez2remember · Post by **ez2remember** » Mon Apr 12, 2004 7:45 am

silvervarg wrote:The biggest danger is that is can easilly fall down and hit your foot with a sharp corner. Perhaps the wires going into the computer is short enough to stop the fall, but then the yank in those cables is not what you really want.

Hee hee, actually my PSU is stuck on with velcro. If you look at the first pick you will see white Velcro between the PSU and my case. I have to apply a lot of force even too remove the PSU, so its unlikely to drop on my foot.

Mike needs a bit of Velcro on his though. We don't want him to be out of work with a broken foot.

Post by **Ralf Hutter** » Mon Apr 12, 2004 12:51 pm

sthayashi wrote:
croddie wrote:Isn't it dangerous to have the PSU out of the case? I thought containing sort of PSU radiation is a main function of a case.
You mean like a metal enclosure around the PSU? Sort of like what's there already?

MikeC has been working with his external PSU computer for some time without any immediate short term problems. Of course, whether or not it's affected his ability to have children, we won't know for a while.

I've had a PSU running my test rig on top of my workbench for over 4 years now, and I still had to have 2 vasectomies to insure that I was "shooting blanks".

Post by **Rusty075** » Mon Apr 12, 2004 2:25 pm

I really, really don't want to know why you had to have 2.

But yes, as long as you're not relying on the PSU to be the only exhaust source, and you're not running some ridiculously high wattage system, 5 volts is generally fine. Just pay attention to the temps for the first few days.

idealcrash · Post by **idealcrash** » Mon Apr 12, 2004 7:18 pm

Is it safe to have the psu totally decoupled from the case? I mean, doesn't it have to be making contact with the case to ground the case properly? How safe is it to install one of those Antec silicon psu kits with silicon washers?

silvervarg · Post by **silvervarg** » Tue Apr 13, 2004 1:41 am

doesn't it have to be making contact with the case to ground the case properly?

You probably have a few other less direct grounding points of the case.
If you have the PSU connected to the motherboard and the motherboard connected to the case through brass standoffs you should have quite good connectios that should give the case grounding.
If you mount the motherboard with mostly plastic standoffs you might have some problems. You might also get the case grounded though other components, like optical drives etc, but I would not want to depend on a specific drive to be connected to get proper grounding.

jpsa · Post by **jpsa** » Tue Apr 13, 2004 5:13 pm

ez2remember, 2 things:
-why is your psu outside the case?
-I think you shoud connect a wire from the psu to the computer case, the groung plug is connected to the psu only and even though the psu has the "0v wire" it should be safer the way I told you (in case of a shotcut or something like that...

vortex222 · Post by **vortex222** » Tue Apr 13, 2004 5:28 pm

i find it safe so long as your other case fans are able to help in pulling the heat out of the computer. some clever ducting or fan placement is a must. on my new server im going to be modding its genaric 350 watt psu so that it pulls the air from the top of the case like the new ARM. and will see how that turns out. i also want to duct it the same way as my main computer

wumpus · Post by **wumpus** » Tue Apr 13, 2004 7:46 pm

I still had to have 2 vasectomies to insure that I was "shooting blanks".

Aurora · Post by **Aurora** » Tue Apr 13, 2004 7:51 pm

LOL... you guys are freakin' hilarious.
I love this forum.

vortex222 · Post by **vortex222** » Tue Apr 13, 2004 8:09 pm

errrr. uhhhh........ ummmmmm.............. hmmm

stuartlee · Post by **stuartlee** » Tue Apr 13, 2004 8:13 pm

Started 5v'ing my psu fan last week on my Dell Dimension 8300 P4 3.0 Ghz, Sapphire ATI 9600 passive cooled vga/dvi card and Hauppauge 350 card, 1 dvd drive, 1 cdrom, 1 60 gb hitachi drive, and a 160 spinpoint...no problems yet, but then again, the way the dells are set up a shroud vents most of the heat from the cpu to an exhaust, although I'm sure that the Sapphire dual screen supporting passive video card and the Hauppuage tv tuner card run pretty hot.

Like others, I don't mind an excuse for another psu...hopefully it won't be another excuse for another mobo & cpu....

vortex222 · Post by **vortex222** » Tue Apr 13, 2004 8:18 pm

you would have to be carefull with del PSU's, there typically not that high of quality, and have very little heatsinks in them. some of them are PFC but most are not. so they can generate lots of heat under load.

and if they blow up, then you need to either get another Dell PSU that costs 5 times more then there worth, or a cable adaptor that costs 5 times more then its worth.

ez2remember · Post by **ez2remember** » Wed Apr 14, 2004 10:03 am

jpsa wrote:ez2remember, 2 things:
-why is your psu outside the case?
-I think you shoud connect a wire from the psu to the computer case, the groung plug is connected to the psu only and even though the psu has the "0v wire" it should be safer the way I told you (in case of a shotcut or something like that...

Running with such low airflow its better to let the PSU cool itself. It is taking cool ambient air from outside rather than the 'used' warm air inside the case. The PSU exhaust air is noticebly cooler than any setups I've had before, even with fans runnning at much higher voltage inside my case. The air is cool and barely warm when running at full tilt. Also I find leaving the PSU outside reduces my CPU temps by about 5C. There is just more room for natural convection.

MikeC also reported lower CPU temps with his external PSU system. He doesn't use any exhaust fans and his system stay pretty cool. Thats quite some feat.

With regards to your question I should ground my PSU, I will run a wire when I get around to it.