fan replacement for PSU

chico1st · Post by **chico1st** » Sat Aug 01, 2009 8:51 am

Hi I have a 560W 80% efficient PSU which I am putting in my P180.

I was going to replace the fan in the PSU because its loud and I was planning to use the SCYTHE SLIP STREAM SY1225SL12M because it got the best rating in the fan round up. Does anyone have any opinions on this? Or should I be looking for something specific in a PSU fan?

The PSU uses a 2 pin-connector if it makes a difference.

sonic6k · Post by **sonic6k** » Sat Aug 01, 2009 9:51 am

I have also think of fan swap trick for PSU. However you need realize starting and operating voltage of PSU fan and SCYTHE fan. PSU fan maybe starting voltage much lower than SCYTHE fan require, or PSU fan operate at voltage too low to SCYTHE fan. Also PSU fan speed up when heat build up, but SCYTHE fan if connected to motherboard only offer constant speed, can make complication if computer have high load! Finally PSU fan most likely of ball bearing, but SCYTHE fan sleeve bearing can wear out if have prolonged use much quick than ball bearing, because direction of fan non vertical.

ADDENDUM: I check SPCR article and have data on SCYTHE fan. Start voltage of SCYTHE fan 2.4V and of 4.0V operating voltage producing 20 CFM. Can work, maybe can not, but will help much if you give more information of PSU.

chico1st · Post by **chico1st** » Sat Aug 01, 2009 12:57 pm

the PSU is a SST-ST56F 560W, on this site I found it by searching ST56F

JamieG · Post by **JamieG** » Sat Aug 01, 2009 3:23 pm

The Slipstream fans are sleeve bearing fans so they can wear out a little quicker and/or make more noise if they are mounted horizontally, like in a PSU.

Also, 1200rpm fans may be a little slow at typical PSU fan voltages if you are aiming to wire the fan to the PSU's fan wires. This is because most stock PSU fans are around 2000rpm at 12V but are quieter because typically PSU fans range from 4V to 7V at idle to average loads. Since most people overestimate how much power their system needs, PSU fans rarely go anywhere near their top speed (usually this only happens when the PSU is getting hot and near full load). Therefore, you should choose a fan with reasonable airflow at low voltage, which is why a higher rpm fan might be advisable, so bear this in mind when choosing a fan for a PSU swap.

My personal preference is a Scythe S-Flex 1600rpm fan, as it features a fluid dynamic bearing that apparently does not suffer when it is horizontally mounted and has a starting voltage of approximately 4V from memory. I've used this fan in a fan swap for my Zalman PSU in my P182 gaming system and I can't hear the PSU anymore.

jessekopelman · Post by **jessekopelman** » Sat Aug 01, 2009 3:38 pm

An alternative is to run your fan at a constant voltage from a normal 4-pin molex connector coming from the PSU. This is what I do. With this method, start voltage of the fan vs. PSU control is irrelevant. Whether this is a good idea is probably dependent on the demand range of your system. Mine runs around 70-110ACW, or probably about 50-90DCW. Waste heat due to AC-DC conversion is both low and fairly constant, so constant fan speed seems quite appropriate.

chico1st · Post by **chico1st** » Sun May 02, 2010 11:18 am

this is sort of embarrasing but im just getting around to this now.

does all this previous advice still stand? Mainly regarding the Slipstream 1600RPM fan (it seems easiest)

and if im using a Scythe SY1225SL12H 120mm 1600 RPM fan, is there any point in using the Scythe SY1225SL12M 120mm 1200 RPM fans in my case?? Wouldnt this end up drowing them out at 24 dBm @ 7V?http://www.silentpcreview.com/article83 ... .html#SS-H

zodaex · Post by **zodaex** » Thu May 13, 2010 2:17 pm

For a PSU I would get the S-Flex over the slipstream for better longevity.