Turn off power supply fan

Speed addicts anonymous.

Moderator: Starfalcon

Turn off power supply fan

Postposted on Sat Oct 20, 2012 7:54 am

I am runing an underclocked system that eat less than 120W at full charge. I have a PSU that can give 350W. My idea is take off the fan from the supply to have less noise in the room. Would like to know if someone have done something similar and if it can be dangerous or I could have an unexpected fire in the PSU.

Thank you.
joselillo_25
Gerbil
 
Posts: 33
Joined: Fri Apr 29, 2005 2:57 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 8:29 am

I'm can't help you on this one as i have never tried it, but i'm just curious, how noisey is that psu fan?
nVidia video drivers FAIL, click for more info
Disclaimer: All answers and suggestions are provided by an enthusiastic amateur and are therefore without warranty either explicit or implicit. Basically you use my suggestions at your own risk.
Arclight
Gerbil Elite
 
Posts: 695
Joined: Tue Feb 01, 2011 3:50 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 9:08 am

Pretty low noise, but, you know, is a drug like overclocking, you always want more (less in that case)

I know that there are fanless PSU but my question is this can be done to a normal one if you do not pass 100-120 w
joselillo_25
Gerbil
 
Posts: 33
Joined: Fri Apr 29, 2005 2:57 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 9:46 am

Fan-less have extra large heat-sinks and extra perforation around all sides to allow extra air flow.

You would certainly shorten the life of your PSU.(how much is hard to tell, depends on ambient, airflow pressure in your case,efficiency{100 watt at 77% =30 watt waste heat in psu; 100 watt at 91%=10 watt waste heat in psu} etc. etc.) heat buildup will certainly kill it however.

alternately, just buy one of the new GOLD or PLAT rated that don't run the FAN at low loads.

You get the silence without paying the high premium of the fan-less along with peace of mind. :wink:

Just depends on what you want to spend. The fanless 400 watt seasonic has come down in price to $119.
mdk77777
Gerbil XP
 
Posts: 346
Joined: Fri Dec 12, 2008 3:42 pm

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 11:01 am

This is a really bad idea. There are PSUs that are designed to shut the fan down when at low load, but PSUs that aren't designed to work this way won't have the passive cooling capacity to keep critical components from overheating.

If you want a PSU that only turns its fan on when needed, buy one that is designed to work that way.
(this space intentionally left blank)
just brew it!
Administrator
Gold subscriber
 
 
Posts: 37479
Joined: Tue Aug 20, 2002 10:51 pm
Location: Somewhere, having a beer

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 11:21 am

"Welcome back my friends to the show that never ends. We're so glad you could attend. Come inside! Come inside!"
Ryu Connor
Global Moderator
Gold subscriber
 
 
Posts: 3506
Joined: Thu Dec 27, 2001 7:00 pm
Location: Marietta, GA

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 12:50 pm

hi, thank you for the answers. I do not like these PSus because they can give so much power that I do not need. If finally will buy one I will buy one of those that connect to a power adapter, like a laptop because I do not need so much energy and they are 93% power efficient and much more cheap.

I only would like to know if they is some really dangerous thing happening turning out the fan like explosions or fires, it does not matter form me that the power supply will have less duration due to an increasing of heat.

I also have the possibility to submerge the computer in monopropileneglycol but I will need to buy a new case.
joselillo_25
Gerbil
 
Posts: 33
Joined: Fri Apr 29, 2005 2:57 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 1:18 pm

I only would like to know if they is some really dangerous thing happening turning out the fan like explosions or fires


Not a high probability.

Chance that you will fry your MB, CPU, or other components when the PSU goes....much higher.

The cost benefit is not there. There are just so many easier, safer, and cost effective solutions. No one in the know will suggest you proceed. :wink:

If finally will buy one I will buy one of those that connect to a power adapter, like a laptop because I do not need so much energy and they are 93% power efficient and much more cheap.


Knowing you will never need more than 120 watts, Pico is the way to go. :wink:

However, efficiency is over-stated.

Yes 96% DC to DC. But the power brick is the one converting from AC to DC. Hence your total efficiency is really much less. However, for a very low watt system, it is silent and the way to go. :wink:

http://www.mini-box.com/12v-16A-AC-DC-Power-Adapter

87% efficiency stated...don't have any independent verification...but assuming it is accurate.

100 watt needed DC/.97= 103 watt at brick./.87=118 at wall = about 85% efficiency....not bad for low wattage applications.
mdk77777
Gerbil XP
 
Posts: 346
Joined: Fri Dec 12, 2008 3:42 pm

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 1:44 pm

If you're willing to crack open the PSU anyway, the 'safest' bet from the PSU perspective - you still need to be careful of the PSU capacitors that could be holding a large charge - is to replace the PSU fan. So, find out what fan it uses and the RPM, and get a lower RPM fan of the same size to replace it. You will want to try to find the startup voltage required for the new fan, the lower the better.

Does the PSU vary fan speed based on load already?
MadManOriginal
Graphmaster Gerbil
 
Posts: 1403
Joined: Wed Jan 30, 2002 7:00 pm
Location: In my head...

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 2:00 pm

mdk77777 wrote:

However, efficiency is over-stated.

Yes 96% DC to DC. But the power brick is the one converting from AC to DC. Hence your total efficiency is really much less. However, for a very low watt system, it is silent and the way to go. :wink:

http://www.mini-box.com/12v-16A-AC-DC-Power-Adapter

87% efficiency stated...don't have any independent verification...but assuming it is accurate.

100 watt needed DC/.97= 103 watt at brick./.87=118 at wall = about 85% efficiency....not bad for low wattage applications.


HI, do not understand this. This mean that a normal PSU could have similar power efficiency than one of those external adapters? I always have suppose that they put the power efficiency of the whole pack, not only the connector.
Last edited by joselillo_25 on Sat Oct 20, 2012 2:14 pm, edited 3 times in total.
joselillo_25
Gerbil
 
Posts: 33
Joined: Fri Apr 29, 2005 2:57 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 2:02 pm

MadManOriginal wrote:If you're willing to crack open the PSU anyway, the 'safest' bet from the PSU perspective - you still need to be careful of the PSU capacitors that could be holding a large charge - is to replace the PSU fan. So, find out what fan it uses and the RPM, and get a lower RPM fan of the same size to replace it. You will want to try to find the startup voltage required for the new fan, the lower the better.

Does the PSU vary fan speed based on load already?


Hi, thank you for your advice. I had read about this problem when dismount a PSU so my idea was simply to cut the fan cable from the outside.

The PSU does not change the fan speed never.
joselillo_25
Gerbil
 
Posts: 33
Joined: Fri Apr 29, 2005 2:57 am

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 3:37 pm

HI, do not understand this. This mean that a normal PSU could have similar power efficiency than one of those external adapters? I always have suppose that they put the power efficiency of the whole pack, not only the connector.


Well, not normal. Depends on the PSU.

PSU are rated for 20% to 80% efficiency.

If you have an older bronze, or only 80% rated PSU, the efficiency drops off quite rapidly at the under 20% utilization.

Say you are pulling 40 watts at idle and 80 watts at full load and your 350 watt is an average bronze rated unit.
SeaSonic SS-350ET Bronze 350W ATX12V V2.31 80 PLUS BRONZE Certified Active PFC Power Supply - OEM

http://www.plugloadsolutions.com/psu_re ... Report.pdf

at 80 watts you are at something like 84% 80/.84= 95 watts at the wall
at 40 watts you are at something off the chart...and it drops rapidly..my guess less 78% so 40/.78=51 watts at the wall.

To get the 85% of the PICO/brick...you need to have a PLAT rated PSU at these low watts.


I always have suppose that they put the power efficiency of the whole pack, not only the connector

Sorry, no.
The 96-98% you see is just the conversion of the DC-DC of the PICO attachment.
You need to look at the AC-DC conversion at the brick to figure out the efficiency of the entire system.

But like I have shown, 85% is pretty good for these low wattage application. You might do better with higher cost more efficient bricks, but there isn't a huge demand for these.
People tend to either buy a complete system or build a power gaming rig...just not a huge market for the DIY Micro computer system.....

Hi, thank you for your advice. I had read about this problem when dismount a PSU so my idea was simply to cut the fan cable from the outside.


and leave live wires uncapped to short out...really bad idea.
mdk77777
Gerbil XP
 
Posts: 346
Joined: Fri Dec 12, 2008 3:42 pm

Re: Turn off power supply fan

Postposted on Sat Oct 20, 2012 3:48 pm

joselillo_25 wrote:hi, thank you for the answers. I do not like these PSus because they can give so much power that I do not need.

While it is true that the higher wattage PSUs are overkill, most PSUs these days are fairly efficient across their entire operating range so you are actually not wasting much power. A 500W PSU that is only being asked to deliver 100W is going to pull around 120W at the wall.
(this space intentionally left blank)
just brew it!
Administrator
Gold subscriber
 
 
Posts: 37479
Joined: Tue Aug 20, 2002 10:51 pm
Location: Somewhere, having a beer


Return to Overclocking, Tweaking, & Cooling

Who is online

Users browsing this forum: No registered users and 2 guests