Connect Power to HDD = No POST

[Myristan]

ya, its definately the power supply. what kind is it?

If that's true, here is what I don't get.

Running with an older Motherboard and processor, this computer runs just fine. Aren't each of these "rails" independant? If so, and it's the power supply, should this problem come up even with a different motherboard and processor? Onlything that's been the same has been the drives and power supply this whole time. So it doesn't make sense to me that it would be a powersupply issue.

 

[Myristan]

Okay I'll just put out what my thought on this matter is...


I'm think'n the motherboard has a short some where.

BuuuUUuut now that I think about it a bit more, can any one tell me if the ATX power cord from the Powersupply to the Motherboard has any datatransfer what so ever? Can the motherboard actually detect, with out a datacable connected, that the HDD or CDROM has power? For some reason I SWORE it could but now that I think more on it, it is sounding PSU related. Krud.

Okay, some one answer this for me..

Do PSU's divy out amps from a pool to all areas? Or does each rail get it's own designated guarenteed pool of Amps to draw on?

Meaning does it work like A or B?

A. 1 pool of Amps. All rails tap into the main pool of Amps for a maximum bandwith of Amps?

B. Each rail has a completely independant pool of amps to work from that is always the same and guarenteed??

And even still that leaves me to wonder... Why would the orignal PC, with a Raedon 9600 256mb video card, network card, soudblaster sound card, along with CDROM and HDD work fine with this Motherboard, CPU, and Memory...

But as soon as I change the Motherboard, CPU, and Memory, it kraps out when I connect nothing but the hard drive to the power supply. Something just isn't clicking for me on this...

 

[Nubius]

so lower 12v rail is better?

No you want higher.

Running with an older Motherboard and processor, this computer runs just fine.

They use less power.

B. Each rail has a completely independant pool of amps to work from that is always the same and guarenteed??

I believe that scenario is the correct one. There's the overall total wattage, in which you multiply the volts by it's ampere so there's just a pool of wattage, but for each rail to actually be specified for a certain rating that means that rail is specifically specified that amount.

Also, I would think it's the motherboard shorting except for the fact you can get into the BIOS....if the motherboard was shorting you wouldn't be able to do that, and since it ONLY crashes when you go to plug in those devices then I'd say grounding is not an issue here.

If you care to put together the older machine that you said it ran on, then you should do that, boot up and see what your rails are running at. If you see the +12v rail down at 11.5 then more than likely the PSU was getting stressed as it was on the older computer and then with the new computer that'll obviously want to draw more power that just tips it over the edge.

What kind of mobo do you have?

Did you make sure to connect both the 20pin power connector and the P4 4pin 2x2 Connector? That little connector takes strain off the +12v rail. (You might already know this stuff, but I just gotta get down to basics incase you don't or for people in the future that read this and don't know themselves so don't think I'm trying to insult your intelligence or anything)

 

[Myristan]

Oookay.

Bios states voltage as follows:

Title Currently At

+2.5v 2.56
+3.3v 3.29
+5.0v 4.94
+12.0v 12.92
Voltage Battery 3.20


Dunno what the heck the 2.5v is cause it's not listed on my Power supply.

Old motherboard is a K7VTA3 v5.0 KT333. I'd just use this damn old board if it supported AGP 8x. grr.

Keep in mind that I don't get the apparent short unless I plug in the power to a CDROM Drive or Hard Disk drive. I can get into the bios if I have no drives hooked up to power.

It almost seems like this is the situation...

Motherboard hooked to power and Hard drive hooked to power.

Power ON.
Motherboard initializes.
Powersupply detects Motherboard startup and reports to motherboard it's total power usage, that the power supply has multiple loads, or that there is just "something" else working on the power supply and the motherboard needs to find out what.
Motherboard then does a initial "Any one there?" out to it's potential devices.
<BZZZ PoP!> System hang or imediate power off.

This all before the bios display's connected hard drives and after Memory and Processor have been displayed.

Don't know if the 741GX-M does this but seems like a likely culprate.

Especially after checking the voltage my um. rails are running at..


Senerio B would be no power output to any other device other than motherboard.

Motherboard doesn't here a report of devices utilizing power.
....

Only problem with this theory is that it would still search just the same for devices.

It is sounding like a power supply issue huh?

Could it be the fusible link in the powersupply? Perhaps that's just old and decrepid and is popping more now with the higher load from the new hardware...

 

[Myristan]

Eh Nubuis,

Based on my last post what do you think is the best course of action? From what I read in an earlier post of yours, regarding the 12v rail having weak amps at 16A... That confuses me based on the next line or two you state that most come with 15A.

Also, the manufacturer "Colorcases" of this power supply states that they have a fusible link in all of their power supplies. Do you know any way this can be tested to verify weather or not it's getting overworked?

One last thing... How can I tell which wires coming from the Power Supply run on which rail? Or do all of the wires coming out of it run on the same rail? Perhaps the voltage is good but the amps it's pushing are tweaked some how?

Is there a utility I can throw up on this computer and check it with? I'm currently using the old Motherboard and Processor now to navigate through this thread and what not. Bout to go back and play some Dark Age of Camelot for a bit to kill the rest of the night. ;p

Just looking for a direction to go with this. Up until this point I was just going to ship back the motherboard and hope the new one that comes from RMA is more functional. But now I'm not so sure... erg.. Any insight/input would be great!

 

[Nubius]

Yeah about the 16a - 15a I was merely saying that 16a IS fairly weak, but it's odd that yours was infact 16a when most generic PSU's come with 15a. I kind of worded it wrong, but yeah 15-16A still isn't that great.

Now, looking at that 12 volt line your BIOS says 12.92....that's a fairly large 'spike' I guess you could say in that rail. 5% fluctuates are to be expected in lines but that's 7.5% fluctuation or so, so it would seem that the +12v rail is getting taxed way more than it likes.

Regarding how to tell which wires are what rails it's this:

Red = +12v
Black = Ground
Yellow = +5
The +3.3v rail is in the main power connector to the mobo.

I know nothing of the fusable link though.

You can use Speedfan, Motherboard Monitor 5, SiSoftware Sandra, all of those will tell you voltages which is mainly what you're looking at right now.

Like I said from that BIOS reading of 12.92 that says to me that the +12v is getting overworked

 

[Myristan]

So when you say that the 12.92 is getting overworked. Would that indicate that it's drawing to many amps thus the voltage goes up?

 

[Nubius]

Yeah I believe basically what's happening is when the +12v in this case gets overworked then it tries to supply the extra Amperage because basically your hardware is demanding that extra power which is simply can't give.

 

[Myristan]

Well I went out and got a new Power Supply. 80 bucks later. grr.. But any who..

Looking at my old power supply and looking at power supplies in the store, it would appear that the Output table on the PSU actually show's how the watt's are pooled for each rail to use. My Current power supply's table show's that the 450W entire power available is just one pool of power.

I got an Ultra 500 Watt ATX Power Supply. It has a 480W pool for just the +3.3v, +5v, and +12V rails. If the table truley depicts how the power is split up, the 12V is separated much better with this PSU.

On top of that this PSU has the following.

+3.3v 28A
+5.0v 38A
+12v 25A
-12v 0.6A
-5v 0.6A
+5VSB 2.0A

Overall higher amps with WAY more amps on the +12v rail. I'm going to try it out tonight and see how it goes. Though I am kind of worried at jumping from 16A to 25A on the +12v rail. Dunno if to much can hurt... Hope there's some comfortable regulators in some where. =/

 

[Nubius]

Nah man there's no such thing as too much. Your hardware calls on the power as it's needed so it's not like the +12v is forcing out that Amperage. You could have a 60a rated +12v rail and it doesn't matter, cause the hardware only uses what it needs.

The ultra PSU's are really good PSU's IMO and hopefully this should square you away.