New PSU for HTPC-can't have bottom mounted 120mm fans

PSUs: The source of DC power for all components in the PC & often a big noise source.

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Kwiet
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New PSU for HTPC-can't have bottom mounted 120mm fans

Post by Kwiet » Sun Sep 11, 2005 7:51 am

I am a little stumped :?
My HTPC uses a Cooler Master 610 case with full size ATX PSU and microATX motherboard. As of now, my Zalman 400W ATX power supply works fine but I am looking towards the future. The Zalman (A series) has a single 15A rail that has no problems handling a A64 3000+, X700 Pro, Theater 550 card and two hard drives. The projected upgrade path has me a bit nervous though.
In the next 12 months, the HTPC will grow to 4 hard drives, a dual-core A64 and a faster DVD burner. Presently, it has 3 case fans and other typical things in the box. Hopefully, the new parallel reading type hard drives don't pull too much power but I know the A64 dual-core 4800 (dual 2.6GHz) CPUs won't be too kind to the 12V rail.
I figure I could use a new dual rail 12V power supply to prevent the Zalman from spooling up and getting loud feeding the 12V line. The problem is the power supply sits on the base of the computer so I have different options. The most simple thing to do is another power supply with a single 80mm fan--hard to find one that is quiet. Antec makes their dual 80mm fan power supplies that should work but I like the Seasonics for their efficiency.
If I turned a Seasonic upside-down, there would be about 20mm clearance between it and the top of the case. I am afraid it would choke the intake and force it to speed up. My other option would be to cut a hole in the bottom of the case and put the Seasonic in normally. I could get some of those boutique audio-style "feet" that would raise the case up 40mm and cut vibration. It would work but should I do it?
Using an Antec Phantom 500 is another option. I don't like the idea of it sitting there cooking my case though--the CPU sits next to the power supply.
Should I go with a Seasonic 430W and cut the case so it is a "bottom breather"? Get one of those dual 80mm fan Antecs or ???? The Seasonic would add heat to the system but the dual fan Antec would take it away. I like quiet but it is not the ultimate in critical--my computer is a meter from my ears and is very quiet now. To keep the inside of the computer cool, the Antec would be the best but I like the Seasonics better.
What to get? Seasonic 430W or Antec dual 80mm fan 450W???

MikeC
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Post by MikeC » Sun Sep 11, 2005 8:07 am

Yet another recommendation to look at http://store.seasonicusa.com/index.html -- Seasonc USA's web shop. They still have stocks of Super Silencers, including refurbished 460s with 3-yr warranty for $54.

sgtpokey
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Post by sgtpokey » Sun Sep 11, 2005 8:08 am

Hmm, I don't believe you actually have a aproblem: you may have out-thought the issue.

I use the same case with a bottom mounted psu 12cm fan (I use a 350 watt Fortron Source).

The "bottom" mounted fan in this situation is actually on the "up" side once you install it.

Theoretically you may lose some hot-air exhaust capabilities in an arrangement like this but in practice I have never noticed any problem.

So basically there's no problem with you using a 12cm bottom mounted fan. It'll still exhaust more total air out of your case then any quiet 80cm psu.

Kwiet
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Post by Kwiet » Sun Sep 11, 2005 9:23 am

:oops:
Forgot to mention one thing, the 4th drive will be mounted on top of the power supply inside a Zalman heatpipe hard drive isolater/passive cooler. The bounces the 120mm fan PSUs off the chart if I mount them upside down.

After reading some more about the Antec dual-fan models, I prefer the Seasonic power supplies for their better efficiency and more robust build quality. That narrows it down to the 460W that MikeC mentioned (great find!) or if I want dual rails, put the S12 430W in and cut a hole in the bottom of the case and "jack it up" with cushioned feet to give it breathing space.

I know it sounds odd to cut a hole in the bottom of the case to feed the power supply but I have no problems cutting holes. Above my XP90 heat sink is a 120mm vent with the fan blowing straight up and out of the case. To make the bottom breathing S12 viable, cut the hole--put vibration isolating feet on the case to raise it up and put a deflector plate behind the PSU to divert the hot air blowing out away from my hard drives/optical drives. I have the CPU "exhausting" out the top of the case, an Arctic Cooler venting the video card out the back and a 60mm fan exhausting also.

Any reason I should not go with a "bottom breathing" S12 over a 460W Seasonic? There is always that sneaking feeling I am missing something with the design. I'll just have to remind my wife not to put papers under the computer. :shock:

MikeC
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Post by MikeC » Sun Sep 11, 2005 9:48 am

There is no intrinsic advantage of dual 12V rails. As long as the 12V current capacity is adequate, two or one rails doesn't matter. The two rails come from the same 12V source anyway...

Kwiet
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Post by Kwiet » Mon Sep 12, 2005 8:10 am

Mike,
True, it really does not matter and I have the 20 to 24 pin connector and all the SATA power converters. The 80% efficiency of the S12 can be blinding, it is only a percent or two difference. The problem with the bottom breather is it will add heat to the box and the 460W will take it away. Thanks for the tip and now to get that Paypal account quivering again.

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