Need Advice on Mod for Antec 350W Smart Power PSU

offroad · Post by **offroad** » Thu May 22, 2003 7:21 am

Want to reduce noise on Antec 350W Smart Power but keep decent airflow for fairly cool operation and decent life.

Unit has 92mm intake and 80mm exhaust fans. At least on the bench, the stock fans seem to run fairly slow but have mechanical noise like a groan.

I have 92mm and 80mm Panaflo L1A's ordered but not sure which (or both) fans to use and whether to just hook them up to PSU internal connections or what.

Which option should I use:

1. Replace both stock fans with Panaflo's, and hook to internal PSU connectors.

2. Remove old 92mm, and replace stock 80mm with Panaflo and hook to internal connector.

3. Remove old 80mm, and replace stock 92mm with Panaflo and hook to internal connector.

4. Some combination of Panaflo's at non-stock voltages.

I'm kind of leaning towards option #3 since this would give more airflow and move the fan inside the case. If I do this, should I close up the vents facing the front to make sure all intake air exits the case?

I will be trying to use fan isolators on whichever fan/fans I use. The 80mm is so close to the PSU board if I leave an 80mm in, I will have to grind off either a bit of the fan or the board due to the thickness of the isolator.

Any opinions on which fan/fans to use and at what voltages or stock connections is greatly appreciated.

I don't need this PSU to be silent, just want it to be quieter without shortening its life alot.

Thanks.

Fatal_eXception · Post by **Fatal_eXception** » Fri Aug 22, 2003 7:54 pm

What a pity noone has replied to your post. I have been thinking about doing exactly the same! and like you, I'm not sure what exactly I should do.

Did you end up doing anything, and if so, what was the result?

Will_Corrigan · Post by **Will_Corrigan** » Fri Aug 22, 2003 10:52 pm

Hello, gentlemen. I received an SL350 with my SLK3700 and upon hearing it in action, quickly resolved to remedy the situation.

After removing the 92mm fan entirely, I wired an L1A to the PSU fan header and gave it a whirl. However, even under full load, the fan failed to spin up to any appreciable speed. Moving on, I wired the fan to a Molex connector (12V rail) and tried again. Plenty of airflow, but now I was getting rather a lot of turbulence noise. Tried again with a 68 ohm resistor (8V or so) and haven't looked back since.

A few caveats: this mod will almost certainly raise CPU temps so make sure you have some breathing room. Additionally, some rudimentary duct work would not go amiss, both to ensure that 1). hot air from the CPU goes out the rear exhaust and not into the PSU, and 2). that the PSU is being fed (relatively) cool air from the 5.25" drive bay.

Fatal_eXception · Post by **Fatal_eXception** » Sun Aug 24, 2003 6:05 am

Hi. I decided to go ahead and experiment on my PSU (along with a bunch of other mods). I took out the PSU and used a switch in the ATX power connector to turn it on, and noticed that air was coming OUT of the vents! The 92mm fan was too strong for the 80mm and this would seem to be to be allover pointless. The 92mm fan was also very loud, much louder than the 80mm by itself, strangely. So I disconnected the fan while leaving it in the PSU and taped over the fan hole, to encourage air to pass over the components through the other vents that would be sucking in cooler air.

It's been running for a day now with no problems, though I haven't put it under much load.

I have a 120mm Vantec Stealth fan at the rear near my Zalman CPU fan (a 6000AlCu, suspended over the flower HS), which should suck out the hot air from that, thus negating the need for a PSU fan above the CPU.

It's pretty quiet now, much more than before... except now my graphics card fan has started to tick a lot!

This is pretty much my first major mod, what do you think?

FLD · Post by **FLD** » Tue Sep 02, 2003 8:46 am

Hi! Did anybody try to remove the PSU rear 80 fan, just leaving the 92mm belly fan? (option 3 above?)

Depending on how stuff are set up inside the PSU, the 92mm might be able to blow air all the way to the rear hole (now that you have removed the rear fan). Might result in less turbulence at the rear.

tjoff · Post by **tjoff** » Wed Sep 03, 2003 3:08 am

I have an similar Antec powersupply and I have thought of having an 120mm fan istead of the 92 mm fan. The 120mm fan would be mounted outside the powersupply with som kind of fanduct.

I don't know, but my hopes are that that would allow me to run the 120mm fan very slow and that the turbulence sound wouldn't be as load becuase the fan isn't that close to the components and because the duct would have some kind of cross in the middle to prevent the air to circulate that much.

It's just a thought and I don't know if I have enough space for it in my case.

Another idea I've had is too simply reverse the airflow in the powersupply having the 92 (or bigger) fan 'sucking' air from the powersupply and having it blown out the case (the powersupply would be mounted with the 80mm fan down or in the top of the case). Wouldn't that minimize the turbulence?

SometimesWarrior · Post by **SometimesWarrior** » Wed Sep 03, 2003 3:37 am

tjoff wrote:Another idea I've had is too simply reverse the airflow in the powersupply having the 92 (or bigger) fan 'sucking' air from the powersupply and having it blown out the case (the powersupply would be mounted with the 80mm fan down or in the top of the case). Wouldn't that minimize the turbulence?

Hi tjoff,
The 120mm ducted-fan option is certainly an idea, if you have room below your PSU to mount the duct. With the new 120mm-fan PSU models coming into the market, you can see that this idea not only has merit--it works!

Sucking air into the PSU may not work quite as well, though, because of the possibility that air will simply bypass all the components and go straight from the vent to the fan! 80mm fans work well when sucking air from the front of the PSU to the back because air is "dragged" across the length of the PSU, but if the fan is mounted at a 90 degree angle in the middle of the PSU (like a 92mm or 120mm fan would have to be), then you may need to add some ducting to the PSU or fill in empty space between the fan and the vents to ensure useful airflow across the PSU components. You may also want to pull air from both the front and the back of the PSU, so that you are cooling all PSU components.

In one of my experiments, I flipped the 80mm fan I installed in my 400W Antec PSU from "suck" to "blow", so that it was pushing air into the PSU from behind the case. My system locked up after 30 minutes of on-time, though, and I almost never see it do that. It could have been that the fan-flip affected system components other than the PSU, but the effect would have been marginal because the PSU airflow is separated from the rest of the case via a duct to a front 5.25" bay.

The lesson learned from my experiment: it's not just how much airflow you have in the PSU, it's how the air is used! By flipping the fan, I probably hindered airflow to components on the opposite side of the PSU case.

Whatever experiments you try, please report your results. Good luck!

SixToes · Post by **SixToes** » Thu Sep 04, 2003 2:43 am

I've been thinking about modding my True330 as well.

I like the belly fan only option, but I think you would have to block the vents facing the 5 1/4 drive bays as otherwise hot air from the CPU area will get blown out of them back into the case. Even then I'm concerned that warm air will mostly get blown around inside the PSU as the airflow path is far from smooth through it.

Maybe it would be better to remove the belly fan and block that hole up, replace the rear fan with something quieter, and enlarge the vents facing the drive bays so more air can be drawn in over the PSU heat sinks.

Anyway the next stage for me is to suspend my HD as its the noisiest component at the moment - this will have to come a bit later!