why aren't power supplies external?

[hahher]

less heat, possibly passive (less noise), smaller case


could an external psu (>350w) be passive?

 

[corkyg]

I would not envision a very big market for such a configuration. That is something only a techie would go for. We have a lot of outside, small boxes now. Plus - getting all the power cables to all internal devices and the motherboard would create a spaghetti situation and be much harder to assure and certify EMI shielding for the system.

The vast majority of computer shoppers want to buy a single box that is for them, plug and play.

If you want that configuration - then build it. Yeah - it could be done, but it would add to the cost and also create more problems than solutions.

I really have never understood the big deal about noise. I like to know when things are running - silence would detract from that.

 

[EeyoreX]

less heat, possibly passive (less noise), smaller case

could an external psu (>350w) be passive?

The amount of heat would be the same. The only difference is that the heat would be dissapated directly into the air, instead of into the case. However, I doubt that the PSU is a significant cause of heat in the case, as most have their own exhaust fan, so this point is really a non issue.

How much smaller of a case do you want? Are the Shuttle and their like SFF computers not small enough? Even if they are not, you aren't going to get components that much smaller for the PSU size to matter. If you really want components smaller than what you get in a SFF system, get a laptop.

I agree that most people do not want yet another "box" outside the "box" that is their computer. I have enough crap already, and I just have a DSL modem and a router. I am too lazy and unskilled to easily, elegantly modify my case to incorporate these items. I certainly don't want a PSU with all the extension cables (or however you get the power from the PSU to the components) snaking around my desktop. IMO, the simple reason that this won't happen is that current PSU technology is an efficient solution. There is no need, and I daresay no real desire, to have an external PSU.

\Dan

 

[WackyDan]

Lets see... Shuttle uses that on one of their SFF's.... IBM used in on one of their All in One's... I think X40 Netvista or X41???

Dell and HP have also done it...... Most Corporate shops didn't like it.... While it made service of PSU easier to replace it created and loss and found dept for "power bricks", and introduced one additional standard/part into their environment which added cost to their IT practice.

PSU do serve of purpose of helping pull air through the case, especially in the Tier 1 vendors like IBM, HP, and Dell. I have a feeling though that they will once again go the direction of the external brick as their customers ask for more and more reduced form factor machines.

 

[clicknext]

Biggest reason I can think of is to conserve space, because it's much easier to have everything in one box. Another is possibly more cabling required to bring power to all the components?

 

[hahher]

there would be less heat in your system, so less fans (or quieter fans pushing less cfm) needed inside system. also possibly the external psu wouldn't need a fan either.


do you guys prefer lcd psu brick or internal?


could a 400w external psu be fanless?

 

[Mark R]

Dell's optiplex P4 desktop systems use an external power brick. It's rated for about 160W which is plenty for a P4 2.0 GHz CPU, single HD and CD-RW drive.

We have loads of these machines at work, and they are essentially silent- I'm not sure that they have any fans anywhere - just a massive vertically mounted heatsink on the CPU. They are really compact too - the base-unit is mounted on the back of the 15" TFT monitor.

Looking at the PSUs they are single voltage devices producing a single 12V supply. The PC case has internal regulators to provide 5V and 3.3V rails, basically a tiny module about the size of a 80mm fan takes the input power and provides the extra voltages.

I also wonder if this option may be more energy efficient - ATX PSUs are notoriously inefficient (about 65-70% for a typical supply), whereas you can buy off-the-shelf 12V power bricks with efficiencies over 90%. Power bricks must have high efficiency because they can't dissipate heat very well - whereas the high-performance cooling of ATX supplies can easily deal with a high heat load.