M4-ATX newbie question?

flyerman · 06-30-2008, 06:19 PM

I have a small Dell computer that i want to put in my new leased Honda Civic. I hooked a meter up tp the output of the computer and it showed max 155 watts. Can I replace the power supply in the case with the M4-ATX thst is rated at 250 watts? Do I just take out the power supply in the Dell and try to mount this in the case? Will ot create noise? Sorry for the newbie questions but I am excited trying to get this thing working.

DarquePervert · 06-30-2008, 06:42 PM

The power supply has more than enough output for the Dell PC.
The question is nt the output of the M4ATX, but whether the Dell PC is truly ATX compliant. Many Dell motherboards do not adhere to ATX standards.

As far as mounting the M4 in the case, yes. It should create little or no noise. Heat could be an issue, however.

kibble · 06-30-2008, 06:59 PM

I agree with Darque. I've taken apart some dell power supplies where the ATX connector was the same size and had all the same pins, but some of the voltages were located on different pins.

You may want to check your power supply and make sure that everything is the same. Newer Dells don't seem have the same thing going on. I've seen it more on older dells.

rogerdugans · 06-30-2008, 08:43 PM

Quote: Originally Posted by kibble

I agree with Darque. I've taken apart some dell power supplies where the ATX connector was the same size and had all the same pins, but some of the voltages were located on different pins.

You may want to check your power supply and make sure that everything is the same. Newer Dells don't seem have the same thing going on. I've seen it more on older dells.

Exactly right.

I am NOT certain exactly when they changed, but Dell USED to switch a few (I think it was 2 or 4) of the wires around to force people to buy DELL replacement power supplies, which cost more.

Since they DID use a standard atx connector, that made it simple for the computer enthusiast niche to use regular power supplies as needed, but the average user was screwed.

Eventually Dell gave up and went with the standard.

I think the change was about 4 years ago, but I am in no way certain.

The good news is that all of the voltages ARE standard, so either way you CAN use any power supply with any Dell- but make sure that the one you have matches the voltages in the m4-atx (or any other psu) before you plug things in.

The info on which wires and when the change happened is on overclockers.com (where I read it years back) and is sure to be elsewhere too.

flyerman · 07-01-2008, 07:54 AM

Here is the power supply but I am not sure if it can be replaced with the M4-ATX.

HP L161NF3P 160 Watt Power Supply
Dell Optiplex GX280 Pent 4

I have been searching to see if it is a standard one but no luck yet. Thanks for the replies.

DarquePervert · 07-01-2008, 08:11 AM

The only way you're going to know is to power up the PSU and measure the output voltage on every single pin that's not a ground.
You can find pinouts & voltages for the pins of a standard ATX connector by Googling. If the voltages on your Dell PSU match those of a standard ATX PSU, then you're golden.
If not, you'll have to make an adapter to get it to work.

rogerdugans · 07-01-2008, 08:30 AM

Looked up a few things-
standard atx pinout

I also looked up the Dell numbers and found a couple of very different power supplies...
At least one of them apparently has an additional, proprietary 6-pin connector.

As stated above- the best way to make SURE is to check all the voltages with a meter while running.

ezzab · 07-01-2008, 08:49 AM

wait i have a dell optiplex gx280 in my car and it has an external power supply, and for that you need a high powered 12v regulator like carnetix's cx-p2140.

kibble · 07-01-2008, 10:15 AM

A GX280, should have a standard ATX connector. I'll double check for you at work. We have one of those.

Is it the one with a socket 775 P4 and a PCIe X16 slot?

flyerman · 07-01-2008, 10:27 AM

I checked the voltages with my MM and compared them to the 20 pin standard ATX layout. They are the same which is good news. I think I will order the M4-ATX which should give me enough power for the computer and Visteon HDRadio.

(ezzab) Why do you have an external power supply? I will look up the "carnetix's cx-p2140".

flyerman · 07-01-2008, 10:29 AM

Yes kibble it is the one with a socket 775 P4 and a PCIe X16 slot. I appreciate all the help.

kibble · 07-01-2008, 11:24 AM

Just took a look. Yes, it does look like a standard 20 pin ATX supply.

DarquePervert · 07-01-2008, 01:40 PM

Quote: Originally Posted by kibble

Just took a look. Yes, it does look like a standard 20 pin ATX supply.

Understand that "looks like" doesn't mean it meets the ATX standard.
There are a number of Dell models that have the standard 20-pin ATX power connector, but the pinout of that connector is different than the ATX standard.

I have yet to see a list of Dell PSUs that indicate ATX compliance or not. But then again, I haven't looked for one, either.

As far as I know, the only way to confirm or deny true ATX compatibility is to measure the voltages on each pin and compare that to the pinout voltages for the ATX standard.

kibble · 07-01-2008, 01:50 PM

Yeah, but they also have different colored wires in different spots. Like the orange for the 3.3V was in a different location. Plus I've messed with plenty of dells and checked the voltages. The GX260's use an identical power supply and those were standard ATX connectors. I just wanted to make sure that the 280 was the same because we don't play with those much and we only have 1 in our office. We got tons of 260's which are practically identical in everyway except for the motherboard.

rogerdugans · 07-01-2008, 02:42 PM

The point is that the Dell CONNECTOR is a standard 20 pin ATX connector but that it is NOT safe to assume that it follows the standards for voltages.

Colors are an indication most f the time, but with Dells it is not safe to assume.

Check the voltages.

If they are NOT the ones stated in the ATX standard you can still use an m4-atx (or other ATX compliant power supply) but you MUST move the pins around so that the psu sends voltage where the motherboard expects it.