Thread: M2-ATX Wont power on PC, fan turns every few seconds

Originally Posted by djjerdog

I am in the process of installing my first CarPC, I have a Commell LV-677 MB using a Core Duo 1.86GHz CPU and a SATA 2.5" 120GB HD. I am trying to use a M2-ATX 160watt DC-DC power supply.

My problem is that when I finally got everything all hooked up I went and fired up the car and after a few seconds all that happens is the fan on the motherboard will spin about a full turn and then stop, about every 3-5 seconds this repeats and that is all I can get it too do, until I disconnect the power.

At first I thought I wasnt getting a good ground, so I checked that and everything seemed good. I did some digging on the forums and found a ton of posts about the M1&2 having problems but couldnt find any issue like this...

I took the PC back in the house and connected the m2-atx to a 350watt power supply and got the same results.

Am I forgetting a step?, Is this another bad PS?, or is it just not enough power?

Have you run a power calculator, to determine that you are not exceeding the wattage on each individual power line, 5v, 12v.

Michael

List all your components. Have you tried removing some hardware to lower the power requirements, like DVD/CD drive, 1 stick of ram instead of using 2, and etc., for testing? Also, can the carputer power on directly from 350W power supply?

Originally Posted by djjerdog

I came up with roughly 130watts, but I am not sure what the motherboards onboard video uses.

The CPU is only supposed to be 31watts.
This is what I have connected:
Commell LV-677 MotherBoard,
T2400 Core Duo 1.86GHz CPU,
1 2.5" 120GB HD,
1GB DDR2 memory.

I really dont think I should be needing more then 160watt?

I understand that you are under total wattage, but you have to figure out if you are exceeding the power available on EACH INDIVIDUAL POWER RAIL. While you may be under 160 watts, you might be drawing 100 on the 5 volt power rail, while the unit can only supply 50 watts. That will keep it from booting, or like you have, once the power is required, it won't boot, it will try, and spin the fan, but when the cpu starts to draw power, it shuts down, and over and over.

Michael

Originally Posted by djjerdog

This is my exact current setup:
Motherboard = Commell LV-677 [25 watts?]
CPU = Intel Core Duo 1.86GHz (T2400) [31 watts]
Video = Onboard Mobile Intel 950 Media graphics accelartor [10 watts?]
Memory = 1 stick of 1GB DDR2 667MHz [10 watts?]
HD = 1 120GB Seagate SATA [5 watts]
Wireless = Asus Mini-PCI (Wireless G)
thats it...

Everything works perfectly fine when connected to a standard 350watt AC/DC power supply in the house.

From what you have listed, should be only about 85W total. I am guessing a bad M2-ATX.

Originally Posted by myzhi

From what you have listed, should be only about 85W total. I am guessing a bad M2-ATX.

You also are relying on total wattage. THAT IS INCORRECT.

Here is the calcualtor I used. http://www.ohmygodmyarmfelloff.com/MP3Car/PSUpower.asp

Next, I looked at the spec sheet for your SATA drive, and it requires 2.2 amps on the 12 volt line. That is almost 30 watts, not 5 watts. (http://www.seagate.com/docs/pdf/data...racudaata5.pdf)

Your memeory stick is at least 16 watts, all on the 5 volts rail, which is about 3 amps.

The processor is about 34 watts, and I believe it is on the 3.3 rail, though it could be on the 5v rail. Assuming 3.3, that is 10 amps, and 5 volt would be 7 amps.

An MB with on board devices use about 1.5 amp on the 3.3, 1amp on 5 volts, and .5 on 12 volts.

These numbers are the best I could find, and might be higher or lower, but will be a start.

Here are the specs for the M2, http://resources.mini-box.com/online...etype%3Apdf%22

Each rail has a max of 8 amps, 3.3, 5, and 12 volts.

The 12 volt rail seems fine, since it has 8 amps, and you are using about 3 amps. 3x12=36

Now, lets look at the 3 volt, using the worse case scenario,

the MB, 1.5 amps and the processor 10amps. That is 11.5, over the amperage of the M2. 11.5x3.3=38

Now, lets look at the 5v line, assuming the worse case scenario

The MB is 1amp, memory 3amps, CPU 7amps. Again, you are over the amps rating of the 5 volt rail. 11x5=55

Even if the CPU voltage is split, you are taxing both the 3.3 and 5v rails. If it uses only one of them, you are DEFINITELY over on either rail.

NOTICE that in any situation, you are under 160 watts. 55+38+36=129, and that is assuming the absolute worse case scenario on BOTH the 3.3 and 5 volt rails AT THE SAME TIME.

That is why your system won't start.

Is there a reason you did not follow my advice and run a power calculator on your system and see if you exceeded the amperage of a single rail?

Michael

Originally Posted by Wiredwrx

You also are relying on total wattage. THAT IS INCORRECT.

Here is the calcualtor I used. http://www.ohmygodmyarmfelloff.com/MP3Car/PSUpower.asp

Next, I looked at the spec sheet for your SATA drive, and it requires 2.2 amps on the 12 volt line. That is almost 30 watts, not 5 watts. (http://www.seagate.com/docs/pdf/data...racudaata5.pdf)

Your memeory stick is at least 16 watts, all on the 5 volts rail, which is about 3 amps.

The processor is about 34 watts, and I believe it is on the 3.3 rail, though it could be on the 5v rail. Assuming 3.3, that is 10 amps, and 5 volt would be 7 amps.

An MB with on board devices use about 1.5 amp on the 3.3, 1amp on 5 volts, and .5 on 12 volts.

These numbers are the best I could find, and might be higher or lower, but will be a start.

Here are the specs for the M2, http://resources.mini-box.com/online...etype%3Apdf%22

Each rail has a max of 8 amps, 3.3, 5, and 12 volts.

The 12 volt rail seems fine, since it has 8 amps, and you are using about 3 amps. 3x12=36

Now, lets look at the 3 volt, using the worse case scenario,

the MB, 1.5 amps and the processor 10amps. That is 11.5, over the amperage of the M2. 11.5x3.3=38

Now, lets look at the 5v line, assuming the worse case scenario

The MB is 1amp, memory 3amps, CPU 7amps. Again, you are over the amps rating of the 5 volt rail. 11x5=55

Even if the CPU voltage is split, you are taxing both the 3.3 and 5v rails. If it uses only one of them, you are DEFINITELY over on either rail.

NOTICE that in any situation, you are under 160 watts. 55+38+36=129, and that is assuming the absolute worse case scenario on BOTH the 3.3 and 5 volt rails AT THE SAME TIME.

That is why your system won't start.

Is there a reason you did not follow my advice and run a power calculator on your system and see if you exceeded the amperage of a single rail?

Michael

1) The power calculator you posted is missing way too many major variables (cpu, HDD, and etc.) to be truely helpful.

2) Intel says cpu uses 31W.

http://www.intel.com/products/proces...eduo/index.htm (Click on View processor numberΔ details link)

3) Your Seagate PDF example is for desktop 3.5" SATA harddrive. He's actually using a 2.5" SATA laptop drive. Wattage for this drive seems to be 0.28W (standby) - 2.2W (seek).

http://eshop.macsales.com/item/Seagate/ST9120821AS/

4) DDR2 uses 1.8V compare with 2.5V in DDR. Thus, it should be less than DDR's 10W rating, around 7.2W. Not sure where you are getting 16W from.

http://carpc.kyferez.com/Tools/PSUWattageCalculator.php


A "working" M2-ATX should power his system. My carputer should be more taxing on the M2-ATX than his setup.