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 Post subject: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 4:06 am 
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At Computex 2011, Antec has revealed the Solo II. In a number of ways, Antec has kept true to the original design. Perhaps sadly, they've also kept true to the top-mounted PSU even though the industry has shifted towards bottom-mounting.

As I see it, the top-mounted PSU holds two disadvantages:

1) the PSU is used as an exhaust fan. It's not good for PSU to pull in hot air. That's why Antec put it at the bottom with the P18x in the first place.

2) Though Antec Solo has holes for cables to be routed behind the mo-bo tray, the thought of cables dangling down from the top gives me nightmares. If bottom-mounted, the cables could just be placed on the floor where they would not obtrude a neat & tidy built. And of course, the airflow.

A small advantage: If only one exhaust fan is used, the PSU would help exhaust heat, thereby aiding in keeping temperatures low. Maybe that's the reason why the Coolermaster Sileo 500 performed well thermally in SPCR's review.

What's your opinion on this?

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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 5:56 am 
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Top mounting allows for a smaller case and shorter power cables. But the power supply should have its own air chamber (like NSK3480).

Note that with a (semi)-fanless power supply, top mounting may result in the power supply being an air intake. Although the power supply works fine like this, it steals air flow from the rest of the case, so you may have to add a front fan.


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 6:41 am 
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I've yet to see a convicing argument that it makes any difference. Separate chamber - yes, it is a great idea. Top or bottom - little importance.

Quote:
top mounting may result in the power supply being an air intake


I see that as an advantage, that's the way "passive" cooling should work. Modern PSUs produce minimal heat (like what, 10W for every 100W delivered?) - it doesn't take much to disperse that.

Quote:
the PSU is used as an exhaust fan. It's not good for PSU to pull in hot air. That's why Antec put it at the bottom with the P18x in the first place


Well, P18x is a different case as it has a separate chamber. As for the hot air being pulled in, PSUs are designed to handle that. Besides, what's the temperature of the air entering a PSU? I would guess it's only 20*C above ambient.

Quote:
Though Antec Solo has holes for cables to be routed behind the mo-bo tray, the thought of cables dangling down from the top gives me nightmares.


Modular PSU is the way to go :)

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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 10:06 am 
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Looks like one could bodge in a fairly effective floor under the PSU just like with the old Solo. But yeah, this revision could have been out like five years ago. Today they might as well have left the design to die off in my opinion. There's room for an extra long graphics card in there, but why would one use this case such a power hungry thing? The Solo 2 makes no sense today.

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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 11:54 am 
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I feel like bottom mounted psus were more important when hot air would cause psus to become extremely loud in the past. There's a lot of options for psus that can handle hot air many times better in current times, especially when the X-series can stay passive up to a pretty good load.

It's still helpful if you want to guarantee the highest low noise load and don't mind the cable routing or bigger case.
But if you prefer smaller cases with shorter cables, top mounting looks like a much better idea. That's my two cents at least and it's obvious where my preferences lie :)

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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 11:55 am 
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Bottom mounted PSUs have no advantage at all over bottom mounted PSUs regarding cable management if they both have the same clearance and adequate holes in the motherboard tray.
I've seen loots of people modding their top mounted cases really neat and my own build with my Chieftec case also had the means of being tidy. Lian Li and Lancool are great examples of cases with good cable management and top mounted PSUs.

PSU cooling and acoustics is another matter however, top mounted PSUs will be at disadvantage here.


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 7:12 pm 
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My opinion is bottom PSU is far superior. Hot air rises, and a top mounted fan (or opening without a fan running) can be a big advantage, and can be utilized (without blocking the opening) to reduce the total number and/or speed of fans on a quiet PC build.

I would look at the new (not yet released) Antec P280, which looks like a larger Solo II with bottom PSU. Unlike the P183, the new P280 has a mesh vent under the bottom mounted PSU, and some other nice features such as external USB and audio ports on top front edge of the case.


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Wed Jun 01, 2011 9:43 pm 
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like others have said as long as the PSU's intake air isn't warmed by other components it should make no difference what so ever, other than the fact the whole system may appear a little bit top-heavy.

I really like how in the RV02 and FT02 the PSU can draw air from the side opening, and expelled through the top as the PSU and placed at 90 deg angle. little disappointing that they took out that feature in RV03


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Thu Jun 02, 2011 12:52 pm 
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m0002a wrote:
My opinion is bottom PSU is far superior. Hot air rises, and a top mounted fan (or opening without a fan running) can be a big advantage, and can be utilized (without blocking the opening) to reduce the total number and/or speed of fans on a quiet PC build.

I would look at the new (not yet released) Antec P280, which looks like a larger Solo II with bottom PSU. Unlike the P183, the new P280 has a mesh vent under the bottom mounted PSU, and some other nice features such as external USB and audio ports on top front edge of the case.


that bottom vent doesn't do much for people with carpet.

assuming i get a P280 (and i probably will), i'll have to run the PSU upside down.

as for top vents, if there isn't a fan there it serves as an intake for the fan in the rear panel. feel it for yourself on a P18x. that may be ok if the computer is out by itself, but if it's under a desk with a rear panel, it's just recycling warmed air.


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Thu Jun 02, 2011 8:08 pm 
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cheers wrote:
that bottom vent doesn't do much for people with carpet.

assuming i get a P280 (and i probably will), i'll have to run the PSU upside down.

as for top vents, if there isn't a fan there it serves as an intake for the fan in the rear panel. feel it for yourself on a P18x. that may be ok if the computer is out by itself, but if it's under a desk with a rear panel, it's just recycling warmed air.
Even without a bottom vent, the PSU is elevated off the case floor on the P280, as also on the P183, so turning it upside down is not mandatory. Even on carpet, you could put bigger feet on the case to get some airflow underneath.

Whether or not a top vent without a fan acts as an air intake, that is only the case (no pun intended) if there is a rear exhaust fan of sufficient CFM. It is possible to run a fan on the CPU only, blowing straight up, with air rising through a fan-less top-vent, and no rear exhaust fan. Obviously, this would be for a relatively low power system, but not all that extreme as one might think.

There is a basic principle of physics at play--hot air rises--and one can exploit that fact instead of fighting against it by trying to force air out the rear at a 90 degree angle.


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Fri Jun 03, 2011 3:47 am 
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m0002a wrote:
Whether or not a top vent without a fan acts as an air intake, that is only the case (no pun intended) if there is a rear exhaust fan of sufficient CFM. It is possible to run a fan on the CPU only, blowing straight up, with air rising through a fan-less top-vent, and no rear exhaust fan. Obviously, this would be for a relatively low power system, but not all that extreme as one might think.

Interesting. Do you think it would be a good idea to cover rear exhaust fan hole in this case to prevent it from becoming air intake?


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 Post subject: Re: Top vs. bottom mounted PSU.
PostPosted: Fri Jun 03, 2011 7:36 am 
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sam2 wrote:
Interesting. Do you think it would be a good idea to cover rear exhaust fan hole in this case to prevent it from becoming air intake?


if your case is under a desk where warm air would accumulate back there, yes you probably would.

my other problem with top blow holes is that they're an easy sound path


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