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 Post subject: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Sat Apr 09, 2011 12:26 pm 
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Joined: Sun Apr 03, 2011 9:52 am
Posts: 3
Hi all,

A week ago, I installed Seasonic X-460 into my P183, and my observations suggest is that having separate PSU chamber is rather a disadvantage for this setup.

In X-400 review, it was mentioned that cases with bottom PSU mount may be advantageous for fanless; it seems to be true, since (in absence of significant forced airflow) hot air will go up because of convection and escaped by system fan(s) (funny that at the beginning of ATX era the PSU was responsible for overall system cooling and now it may be dependent).

However, in P183 there is a inter-chamber wall; it is not airtight but definitely impedes the airflow. Without fan in the lower chamber, it creates a closed space with little air circulation. It should be also noted that P183 lacks any holes in the bottom for air intake which some other cases have. I know it is made to accomodate their non-standard PSUs.

I removed all plastic wall components which freed quite significant openings in the wall. PSU temp seems to be notably lower now (of course it was not overheating anyway in my system which is probably is above 250W only at Prime95+Furmark).

However, what do you think will happen if someone wants to have X-460 at full load (or let's say at 400W) with P183?
Will it do just placed in lower chamber? Using lower chamber fan makes fanless PSU pointless.
Any experience of "heavier" systems with X-400/X-460? Which fan config would you use for such systems?

Using fanless PSU with 400W+ system is maybe not too good idea by itself, since other components will be not that silent anyway, so please take my question as theoretical :)

BR,
Alexander

P.S.: The system is Phenom II X4 965 undervolted to 1.25, with S. Mugen 2 and one Noctua system fan. Video is passive Radeon 5570.


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 Post subject: Re: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Sun Apr 10, 2011 12:05 am 
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Joined: Mon Jun 16, 2008 6:00 am
Posts: 83
Location: eu
I don't have a P183 (yet), but I imagine the best solution for a fanless PSU would be:
1. completely isolate the bottom chamber (cover all holes that connect it to the top one)
2. put in a slow (500 rpm) fan in the bottom chamber (in front of the HDD(s) in the P183)

That fan would be slow enough to be inaudible, but still move some air, some of which would go out through the PSU, if the chamber is isolated.

I imagine the P182 could be better for cooling the PSU, since the fan would be placed very close to it, but if the lower chamber is properly isolated the P183 should work as well.


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 Post subject: Re: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Sun Apr 10, 2011 12:21 am 
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Joined: Sun Apr 03, 2011 9:52 am
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Sounds very reasonable.
Do you suggest to put this fan for intake or exhaust?

I'm asking because my specific system with one exhaust system fan have slightly negative pressure; together with convection (the lower chamber is not absolutely airtight anyway) what ensures that air "naturally" flows inside the case in this setup (checked with the small paper string). Should we help this flow by exhaust fan or reverse it?


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 Post subject: Re: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Sun Apr 10, 2011 10:08 am 
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Joined: Mon Apr 25, 2005 10:00 am
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Location: Grand Rapids, MI
Honestly, I don't get the run on passive PSUs. In most cases, they all suffer from some coil whine that ends up being audible at VERY low levels.

It's much safer and cheaper to find a semi-passive or actively cooled PSU, that are almost dead-silent. I've had Seasonic S12's, Antec Earthwatts, Corsair VX's and several other PSUs, but the quietest one I currently have is the TruePower New TP-750. It is, by far, the quietest PSU I've ever (not) heard.

There are many others out there that are just as quiet. Pick a good brand (Nexus, Seasonic, etc) and go with it.

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 Post subject: Re: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Sun Apr 10, 2011 10:19 am 
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Well, I had Enermax Modu82+ 425 before and since the PC is on top on the table, switching to fanless did decrease perceivable noise. (I have good hearing, so in the night when it is quiet, the main sources of noise are my LCD (will change it eventually) and HDD of course; and I'm pretty sure that decrease of noise is not placebo effect). During the day the difference is not really noticeable.

Semi-passive Seasonic X-series were an obvious alternative, but I think I will never go over 300-350W since I'm not playing 3D FPS... so I've chosen to try fanless.


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 Post subject: Re: Is 183 dual-chamber design good for fanless PSU?
PostPosted: Mon Apr 11, 2011 12:06 am 
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Joined: Mon Jun 16, 2008 6:00 am
Posts: 83
Location: eu
atitarenko wrote:
Do you suggest to put this fan for intake or exhaust?

If the fan was placed in the rear, I'd say exhaust. But since it's in the front, intake seems more appropriate. Also, since the chamber is not airtight, you could run the risk of air being sucked from the top chamber, therefore bypassing the PSU, and it would also worsen the airflow of the top chamber.
So I'd say let it run as intake and try to isolate the chamber, so that as much air as possible is flowing towards and out through the PSU.
This is just theory, I don't have that case so I can't speak from practice.


jhhoffma wrote:
Honestly, I don't get the run on passive PSUs. In most cases, they all suffer from some coil whine that ends up being audible at VERY low levels.

Why would this be an issue of passive PSUs only? Is it something inherent to the way they are made, or are people just more likely to hear the noise they usually wouldn't with a regular PSU?

I believe the semi passive Seasonics suffer from the same noise (which was mentioned here on SPCR) as the passive ones (400/460). But it seems like not all people have this noise issue.

Running a passive PSU + an external fan has some specific advantages over running a PSU with a fan. You can regulate the fan speed, you can cool some other components and if/when the fan breaks or becomes noisier you can easily replace it.


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