Can fewer fans cause more noise?

[Zap]

My wife's system is running an Antec Phantom 350W PSU. It's a fanless unit. Her Lian Li case has an 80mm blowhole and I had installed an Arctic Cooling 3TC, an 80mm temperature controlled fan. Since temperatures have risen lately that fan has been spinning like crazy after the system's been on for a while.

My theory is that if I used a PSU with a quiet 120mm fan, the 80mm fan would not have as much reason to spin up, and thus overall noise will be lower plus perhaps overall temperatures may be lower - the other reason... her system locks up when room temperatures go past mid-70s.

I just received a Seasonic S12 380W that I ordered from CensusPC. It's the older revision since it doesn't have the PCI-E plug (now I have to go find my adaptor) but I've heard the older revision is quieter than newer one since the fan doesn't spin up as aggressively.

I'm going to install it this afternoon and will know by evening if system is quieter. As for lockups... we'll see.

 

[aigomorla]

are you sure its due to temps? Also 80mm fans are kinda crappy if i do say so myself. They give out LOW CMF's at a high noise raitio. You could buy some fan adaptors that convert 80mm ->120mm. Only drawback would be that it would extend a little bit outward. About 1-2inches depending on the adaptor.

Personally if i work with a case with 80mm fans, i'll dremel and drill a new 120mm hole if i can.

 

[996GT2]

Originally posted by: aigomorla
are you sure its due to temps? Also 80mm fans are kinda crappy if i do say so myself. They give out LOW CMF's at a high noise raitio. You could buy some fan adaptors that convert 80mm ->120mm. Only drawback would be that it would extend a little bit outward. About 1-2inches depending on the adaptor.

Personally if i work with a case with 80mm fans, i'll dremel and drill a new 120mm hole if i can.

The AC fans are usually very quiet. But I say ditch the ACF3 for a non temp-controlled AC Fan 8 that pushes 28 CFM at a nearly inaudible noise level. I've got one, and it's hard to hear unless you've got the case open and your ear's practically next to the thing. It also has RPM output built in, another plus. Then add the PSU with the 120mm fan and you should be fine.

 

[dBTelos]

My advice to you:

Cover the top blowhole with some plastic, foam, etc instead of a fan, put the fan in front for a intake and a 120mm in back for exhaust. Put both fans on a fan controller and adjust fans as needed.

 

[Zap]

Originally posted by: aigomorla
are you sure its due to temps?

I re-built the system in December. Last time it snowed here was first week of April. No lockups until last two weeks when indoor temps have hit upper 70s. Turning on A/C "fixes" the problem. I'd say there was a heat issue.

Well, did some changes including using the Seasonic PSU and using some generic fan undervolted to 5v instead of the AC 3TC. Put the AC 3TC on the video card (was also running passive). So far system is quieter. Will see if there are any lockups.

 

[pkme2]

I've changed my LL case fans to Yate Loon 120mm first and then 80mm YLs and they are soooo quiet and soosooo cheap.

 

[Tiamat]

Zap, your thinking makes sense.

Pretend you have X amount of heat in the case.

If you have 1x 120mm fan intake, 1x 120mm fan exhaust, and the 80mm chimney fan; you have some amount of air exchange for that level of noise

Now, if you have the same setup, but now an extra 120mm fan exhausting (whose noise is negligable compared to a full rpm 80mm fan); that 80mm fan probably is rendered less useful and as such will not have to spin up as much. In addition, you could remove that fan all together and find your temperatures still ok.

Not necessarily fewer fans = more noise. More like "less overall air exchange = more noise" where the primary noise source is assumed to be the temp controlled fan which ramps up due to increased accumulation of thermal energy within the case.


Also, the phantom power supply is a heat source in of itself. This heatsource can be significant even though it is very efficient and if that heat is only being exhausted by the chimney fan, then that 80mm fan's sensor will see all of that heat energy and ramp up. The seasonic's fan will work to remove the PSU's heat as well as any other heat in the case.

 

[Zap]

Tiamat, your reasoning makes sense... that 80mm temperature controlled fan was probably working overtime to exhaust heat from the Phantom. The generic 80mm fan running on 5v is really quiet, just the motor clicking from the low speed which isn't too bad. So far it survived really high temperatures yesterday evening without locking, while still being quieter - I think it got over 80º in here.