DC to DC power supplies?

R

RudeCurve

Banned
So I've got an external power supply brick that I use with my Silverstone LC19 1U. The stock unit is rated 120W and failed about a year ago..it lasted several years. I then replaced it with a cheap $17 120W unit that runs at 15V instead of the 19V of the stock one. That lasted only about 9 months. :oops: So today I got a $50 factory Lenovo 170W 20V unit and it's working great so far but it too runs kinda hot. My concern over these external bricks is how hot they get since they do not have fans or vents. There was even a factory sticker on the Lenovo brick that said "Caution Hot". Anyway should I be concerned? :eek:

My setup is not a power hog ie stock FX4100 at stock speeds with IGP based graphics so I'm confused as to why the external adapter gets so hot. Is this normal? :???:
 
Power supplies are indeed not 100% efficient, and if they don't have integrated vents and fans they will get quite warm (heat up until they emit enough blackbody radiation to equal the internal heat buildup, or somesuch. :)) Wether this worries you, or is cause for any concern, no idea. Electronics usually last longer when running cool, but seeing as the PSU is designed to operate in a fanless state you'd expect it to handle the heat levels - for the foreseeable future naturally. Eventually everything fails no matter what...

You may want to put your PSU on a hard floor rather than on fuzzy carpet/rug, and make sure no curtains, drapes or such cover it. Maybe stick on some rubber feet, to raise it off the floor and improve air circulation around it. *shrug*
 
RudeCurve said:
So I've got an external power supply brick that I use with my Silverstone LC19 1U. The stock unit is rated 120W and failed about a year ago..it lasted several years. I then replaced it with a cheap $17 120W unit that runs at 15V instead of the 19V of the stock one. That lasted only about 9 months. :oops: So today I got a $50 factory Lenovo 170W 20V unit and it's working great so far but it too runs kinda hot. My concern over these external bricks is how hot they get since they do not have fans or vents. There was even a factory sticker on the Lenovo brick that said "Caution Hot". Anyway should I be concerned? :eek:

My setup is not a power hog ie stock FX4100 at stock speeds with IGP based graphics so I'm confused as to why the external adapter gets so hot. Is this normal? :???:
Click to expand...

borrow a kill-a-watt or equivalent power meter and check your power consumption under load.

You might want to use a DC-DC adapter with a higher rated peak wattage if you get more than say, half-way to rated capacity of the adapter. Over time, the aging of the capacitors in the PSU have a negative effect of the max amount of wattage it can provide (if I'm not mistaken).

Other things that can cause to reduced lifetime:
- hot environment (what's the ambient temp in the room where the power adapter is located?
- poor characteristics of the power supplied to the adapter (frequent spikes, short interruptions, etc.)
 
Well looks like you're right...it seems to be the DC to DC module since the PC is shutting down again even with the new 170W brick. I guess I just wasted $50...sigh. As an interim solution I ordered a cheap but reliable Logisys full size ATX PSU for $17. I did take a look at the Pico modules but they only work with 12V bricks...sigh. Looks like I will have to get one of their kits which isn't too expensive $80 for their 160W package.
 
I previously owned a HTPC built around an LC19 and I encountered problems with the PSU after a couple of years usage.

I wasn't sure if the issue was with the 19V module or the PSU brick so I ended up buying a 12V PicoPSU for a while. Again, that blew up after a couple of years usage as well.

For what it's worth, I know that you can buy PicoPSUs which accept voltage between 12-25V so, if you got one of those, you could use one of your current bricks (assuming they still work). Providing they have the same connector, of course.
 
Yeah I looked for the variable input voltage Pico modules but it seems only the lower wattage ones support it.

Scott..the brick is a standard AC/DC..however inside the PC there is a DC to DC step down module.
 
Thanks for the link...I will probably just use the cheap full size PS until I upgrade the MB. At that point i may just get the 160W kit to be safe. Ive been using the PC with the cover off for years anyway so its already ugly.:LOL:

I think the Killawat device is going to be needed to see how much power the PC is drawing from the wall.
 
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What mobo are you using that needs a DC-to-DC PSU...? Seems cumbersome. Why not just buy something with a standard ATX plug on the mobo next time? That way you can use a proper, fan-cooled PSU that won't overheat and break down every six months. :) Also, ATX Gold efficiency on many PSUs these days will save you power, meaning lower running cost. An AC-DC PSU and then DC-to-DC, and then further DC-to-DC voltage regulation on the mobo itself means lots of losses and waste.
 
Its the case itself being a 1U form factor that requires the DC/DC setup..normal sized PS doesn't fit inside. Basically you have an external AC adapter like a laptop then you have the DC/DC module inside the case. The MB is a standard uATX. The case doesn't even have room for an internal 1U PS hence the DC/DC setup. The DC/DC module is in the metal cage bottom right in the picture. Notice there's not much room since the case is only about 1.5 inches in height. I could easily mount a small fan on the metal cage to cool the DC/DC module but I already have 3 fans running so I didn't want to add another to the noise output. I originally had a slim optical drive mounted in the bottom left of the case but took it out to put in a Blu-ray drive but just hadn't got to doing it. When installed there's absolutely no room left for much in the case.

4uighw.jpg
 
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Why the ridiculously small enclosure, do you live inside a desk drawer or something...? :) Get a mini-ITX PC or something like that if you want a small PC, that way you get a case that looks nice, doesn't take up much space and can fit proper ATX PSU (AND your harddrives.) Many mini-ITX cases even fit gaming GPUs inside, if you'd like to do some of that as well (I see your PCIe slot is unpopulated, so maybe not your thing?)
 
I really like the low profile look..that's why I paid $200 for the case alone many years ago. It's a very nice looking case and the plan was for it to blend in with my AV gear since it's 17" wide..however when I couldn't find a low profile CPU HSF that fit with the case cover on I just left it and it's been that way for years.:oops:

This summer I hope to revisit that plan with a new MB, CPU and a low profile HSF for the CPU. I also want to go back to one internal HDD and use external NAS and USB drives for media. But yeah I'm not really into PC gaming so the PCI slots never get used.
 
The LC19 is extremely low profile and, though not overly cheap at the time, was a fraction of the cost of the bespoke slim systems such as the Hush fanless systems which were around. The mini-itx systems available back then were extremely underpowered as well so Windows Media Centre wasn't very usable on them. A low-voltage AthlonX2 64 provided more than enough grunt.

I had a very slim AM2 socket cooler (fundamentally a block of copper with some fins and a slim fan) which fitted inside well and my system was pretty much silent (especially with a suspended laptop HD inside!) with the fan and CPU greatly undervolted. That said, I did tend to suffer stability issues after around a year of using each particular motherboard (got through a couple over a few year period). In hindsight, this was probably because there was insufficient airflow to the VRMs with my super low airflow fan.
 
The FX4100 is a slight power hog, maybe can it be undervolted a bit, and have it go at max 3.2GHz instead of 3.6 or 3.8GHz.

You have the modern Pentium 4 there :p
Consider swapping it for e.g. an Athlon II X2 or even a Sempron (which can be unlocked to dual if working or needed). FX4100 is more at home in a regular desktop.
 
Ironically last year at this same time frame I started a thread in the purchasing forum about upgrading to the A10 6700 65W and a new MB...but that actually never happened since I had more important things I used my tax return on..but then today I look at what's available and the A10 7xxxx is tempting at 95W.:LOL:
 
The elusive A8 7600 would be safer to not blow PSUs all the time. But it will be available in H2 2014. Talk about a "soft launch".
 
Nice to have a working desktop again...:LOL: The 480W ATX PS is nice and quiet since it has a ball bearing fan. I'm seriously thinking about making extensions to the wires so I could use the ATX PS externally feeding the wires into the case from the card bracket slot in the back. No need to get the fancy DC/DC PicoPSU.:cool:

Looks like I'll need to do a lot of soldering and splicing though...:cry:

Actually I think it would be better to get extension cable bundles instead...like this one and daisy chain them for longer lengths.

cab-36.jpg


o9l1k4.jpg
 
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Beware resistance losses in the connectors that would drop the voltages going into the mobo. Dunno how much it'd do in practice, but it's something worth watching out for... Also, would look hella unsightly by stacking multiple extension cables, wouldn't it?
 
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