/ Sign-up
Your question

Atom system on power drain

  • Homebuilt
  • Power
  • Systems
Last response: in Systems
February 18, 2012 4:43:28 PM


i have this mobo with atom 330 wich i know has a tdp of 22.5 W, a a-data vitesta ddr2 and a seagate 80 GB ata hdd

Q: how much does it need to power on?

I am afraid of some info on the internet that hdd's can eat up to 30 W on start-up.

I have a pico 80W psu and in my home country i could only find this 3A 12 V DC russian delta c power adapter (at home in Romania). This is a test PC so i could just test it when it's ready, but no harm in asking. It's case is hand-made (7.1 inch * 7.5 * 3.5) from an older one and the pourpose of the test is to have only copper heat-sinks and no air holes in the case and keep the PC running. After this one passes the test i will try a low power high end buit again without ventilation.


More about : atom system power drain

a c 78 B Homebuilt system
February 18, 2012 6:09:08 PM

Everything does try to max draw for a small instant when the computer is starting. I would expect that the max draw would be about 2x-3x of the average draw that you are expecting.

I wouldn't think an 80a PSU would be able to handle it, but it just may work.

The 3a 12v power adapter sounds far too tiny to me, but again it may work I guess.

My gut feeling is that you probably need more wattage than what those things would be giving out.
a b B Homebuilt system
February 18, 2012 7:36:14 PM

At power up, the CPU and the GPU basically are idle. To decrease power requirements, a laptop hard disk could be used. I agree that a 36W power adapter is rather weak, particularly when using a 3.5" drive.
Related resources
a c 78 B Homebuilt system
February 19, 2012 12:32:43 PM

Unless Atom motherboards work differently than every other computer motherboard, the first hurdle isn't whether the PSU can sustain idle wattage, it is the test that comes 1 second after the power button is hit where everything tries to max draw at once to make sure the PSU can handle the max load.
a b B Homebuilt system
February 19, 2012 3:08:38 PM

I never heard of such a test. I've seen systems fail when maxing out everything because the PSU wasn't powerful enough, but I had to run an OS and applications to reach maximum load.
February 19, 2012 3:27:46 PM

Allright so I am back to it just might work.

The 330 will drain 8W, the hdd 30W max from 12V, right?

I will see when I get home... if it fails I'll hotwire another 12 V with more A.

About the case, do you think it'll be too hot?
a b B Homebuilt system
February 19, 2012 5:10:19 PM

How will you monitor the case's internal temperature? It will work as long as it can disssipate heat quickly enough.
February 19, 2012 5:41:40 PM

I won't monitor, just run it. If this one works I'll try another better one in mineral oil.
a b B Homebuilt system
February 19, 2012 6:18:56 PM

The hard disk will probably generate more heat than the rest of the components. Will your hard disk be mounted directly to the case to maximize heat dissipation? Is the case without active ventilation or is it completely closed?
February 19, 2012 6:23:59 PM

it is completely closed/will be
i am building it now and yes the HDD's metal cover is going to be in tigh contact with the case

in the case it gets hot, i'll add a small cooler in the side and make some holes on the other side buttom
a c 78 B Homebuilt system
February 20, 2012 3:09:52 AM

That check is why computers turn on and turn right back off if they don't have a good enough PSU attached, if I am not mistaken. Other things cause this too, but in an otherwise good computer with a PSU that would handle only idling load and no more, it won't start.

Also why a computer will cold start OK when it can't handle the computer's max draw during a sustained load scenario (like when gaming). The PSU doesn't have tons of heat when a cold start happens, but gaming for long periods of time does cause heat to increase in the PSU which reduces its max wattage below what it was at during the POST checks.
a b B Homebuilt system
February 20, 2012 11:34:22 AM

I've tested systems using a power supply that can't handle the peak load and they still powered up fine. I could go into the BIOS or run Memtest86+ without problems.
a c 78 B Homebuilt system
February 21, 2012 12:47:19 PM

I don't think I have seen any grossly inadequate ones boot up just fine, only ones that become inadequate later due to thermal concerns.