Hello,

I have an ultra modular PSU and it appears the bearings on the fan have failed and it is extremely noisy. I've replaced fans before and didn't pay attention to the CFM ratings and the PSU died within a few months. My current fan is the DFS132512H http://en.yltc.cn/newEbiz1/EbizPortalFG ... chcategory. Since it is nearly impossible to find a 135mm fan, I think I am going to try to zip tie a 120mm fan in there. I'd like something that would push at least 70 cfm (will this be okay dropping from 90 cfm?) with minimal noise. Any suggestions?

PSU fans typically have low starting voltages, normally around 4V so you need a fan that will start at 4V or less. As your 135mm runs at 1700 rpm max I would have thought a 120mm with a maximum rpm of around 2000 would be a potential choice. A possible candidate is the Scythe Kama Flow 2 1900 rpm model from sources such as http://www.frozencpu.com/products/10174/fan-653/Scythe_Kama_Flow_2_120mm_x_25mm_Fan_-_1900_RPM_w_Extra_Fluid_Dynamic_Bearing_SP1225FDB12H.html.

As you have identified the only issue is whether a 120 even around 2000 rpm is going to push enough air. There are a large number of PSUs fitted with a 2000-2200 rpm 120 fan as standard, and even then the quieter ones restrict the maximum speed to around 1400 rpm or less. It might be worth checking to see if there is any information about how the fan in your PSU behaves. If it doesn't run the 135 at full speed then a 120 could be OK. It's up to you to decide whether it is worth the risk.

Go for a 140mm fan like Scythe Kama flex 1600rpm, or 1200rpm
You may also use a BeQuiet Dark wings, but it is 1000rpm only.

I can't seem to find the Kama Flex except the 800rpm version. http://www.newegg.com/Product/Product.a ... 6835185158 how about this one? Or this http://www.newegg.com/Product/Product.a ... 6835129057 ?

I don't know how a sleeve bearing fan like the Slipstream will behave, and how long it will last in a power supply. Aerocool... crappy fan !

You can perhaps try one of these :

http://www.newegg.com/Product/Product.a ... 6835426027
http://www.newegg.com/Product/Product.a ... 6835553003
http://www.newegg.com/Product/Product.a ... 6835553004

Scythe KAMA-FLEX 135mm x 25mm Fan - 800 RPM w/ S-FDB Bearing (140mm Mount) (SA1325FDB12L), it moves a lot of air at 800rpm, way more than i seen any PSU fan move, but this is at 12V full. Just wondering why you looking for another version? you want more rpms? One thing about the scythe is that its 135mm but the frame is a 140mm or at least it matches perfectly on my lian li Q08 build (but i used rubber screws). If you can fit the KAMA FLEX, you should be able to fit any other 140mm fan, like Noiseblockers PK series, i own 1x PK1 (on my servemi build) and to me its my favorite 140mm fan atm (running at 12V), i also own 2x PK3 on my notebook cooler, Coolermaster SF19, but by no means they are quiet at 12V, but plays good as the cooler has its own fan controller... but i wouldn't recommend it to run at 12V if you want a quiet setup, but for sure moves a lot air. Personally i think price wise the Kama Flex seems like the best option, as long as you can fit it, it should move more air than a PSU would need, but really depends on how you planning on running it.

Edit: Just in case you still want a higher rpm Kama flex 135mm, check Scythe Kama Flex 135mm Fan SA1325FDB12M (1200 rpm)

I would suspect that this PSU is going to supply only around 4 to 5V up to about 20% or 25% of load, and only after that ramp up the fan to full speed, if indeed it goes that far. Noiseblocker do at least say what the starting voltage is, and it is 4.5V for the whole series. So it means that the PK3 with a top speed of 1700 rpm http://www.frozencpu.com/products/10215/fan-659/Noiseblocker_NB-BlackSilentPro_PK-3_140mm_x_25mm_Ultra_Quiet_Fan_-_1700_RPM_-_27_dBA.html is the closest to being a direct replacement for the existing fan.

Hmm so what do you guys think about running a KAMA FLEX 800RPM or the cougar CF directly off of the PSU 100% duty cycle? I'd prefer not to spend more than $20 for this fan. Thanks