no 4 pin cpu connector from psu used on mobo, so what?


H

hot july

About three weeks ago my power supply went out on my Asus mobo (p4s533 or
something like that). The asus mobo had a 4-pin cpu power connector from the
psu going to it. Well I had a spare psu that had no such 4 pin cpu connector
but I put it in anyway and the computer ran just fine. It's been running
fine for almost a month. Yesterday I turned comp on and got the "no signal"
display on the monitor, which suggests a cpu or psu problem to me. The mobo
does not beep when powered on either. No, nothing wrong with video card or
hdd. I need to know what, if any, damage could had been caused to the cpu by
not running the 4 pin power connector to it? Seems to me if there was a
problem, it just wouldnt boot, sort of like now :) But it did run fine for
three weeks without the connector, so I don't get it.

A link to the pic of the 4 pin connector is below if you need to know for
sure what I am talking about.


http://i10.tinypic.com/29kwduq.jpg

29kwduq.jpg
 
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K

kony

About three weeks ago my power supply went out on my Asus mobo (p4s533 or
something like that). The asus mobo had a 4-pin cpu power connector from the
psu going to it. Well I had a spare psu that had no such 4 pin cpu connector
but I put it in anyway and the computer ran just fine.

Sometimes this will work,when the motherboard ties the 12V
lead on the ATX 20/24 pin connector to the CPU VRM
subcircuit input (where the 4 pin connector is).

As processors began to use more and more current it became a
issue and more prudent to prevent a system from being able
to run like that, rather to require having a separate input
for 12V that is not *common* to the 12V lead on the ATX
20/24 pin connector.

When one does try to run a system as you have, it is good to
measure the 12V level at that 20/24 pin connector, and at
the input to the VRM subcircuit - particularly if the ATX
20/24 pin socket is a fair distance away across the board it
may account for a significant voltage drop.
It's been running
fine for almost a month. Yesterday I turned comp on and got the "no signal"
display on the monitor, which suggests a cpu or psu problem to me.

So far we can only conclude the system is failing to post.
Systems being as complex as they are there are many many
possible culprits but the two most commonly at fault (though
you can only play odds for awhile before you lose) are
motherboard or PSU. CPU is hardly ever suspect, only when
there was an obvious problem with it already such as the
heatsink falling off, or if it ran for quite awhile without
the fan working (though in this case a P4 generation CPU
should downclock itself then shut off, not fail from this
slower thermal rise resulting from a fan failure).


The mobo
does not beep when powered on either.

Does the PSU remain on, fans and HDD spinning?

No, nothing wrong with video card or
hdd.

I take it you mean that you have tested these in another
system and this is how you know they still work?
I need to know what, if any, damage could had been caused to the cpu by
not running the 4 pin power connector to it?

For the time being, assume it is not the CPU because the
answer is that there is no direct damage from that, though
extreme current swings could wear out the board, in theory.
In practice you may have a board that failed regardless of
this lack-of-4-pin-connector, or some other cause.

For example when a PSU doesn't have the 4 pin connector, one
that old tends to be optimized for more current on it's 5V
rail, less on the 12V rail. Continually running a PSU at
peak output on a rail as you may have done would tend to
wear it out fairly quickly. You might disconnect AC power,
open the PSU and inspect it for failed capacitors.

You might also use a multimeter now to measure the voltage

Seems to me if there was a
problem, it just wouldnt boot, sort of like now :) But it did run fine for
three weeks without the connector, so I don't get it.

Some failures happen immediately and others happen by
putting a lot of stress on something over time... with a PSU
it is a bit like burning a candle at both ends with it
turned sideways, you may get more continual output than the
manufacturer intended, but it won't last nearly as long.
A link to the pic of the 4 pin connector is below if you need to know for
sure what I am talking about.


http://i10.tinypic.com/29kwduq.jpg

Inspect the motherboard for failed capacitors as well, and
unless you see a fault it would be good to try a known
appropriate PSU next... you don't mention # of HDDs or the
video card model (it is always good to include a concise
list of all major parts in a system) but generally speaking
I would aim to use a median to better name brand rated for
at least 18A on 12V rail, even better if it can be confirmed
working first on another system.

Also inspect the contacts, especially that yellow 12V lead
on the PSU connector, and the corresponding socket hole on
the motherboard ATX socket - through overcurrent it may have
heated that up, degrading the connection and possibly even
melting or charring the plastic around it. Such a problem
would easily be visible with a strong flashlight if you have
straight line-of-sight into the board power socket.

You didn't mention the specific PSU make, model and wattage
(and in this case the rating for amps on 12V rail too)
either, this would be particularly useful when trying to
assess how appropriate it was.

It is possible to use a PSU without the 4 pin connector, a
few older PSU had reasonably good 12V rail current
capability but in those cases it is best to use a 4-pin
molex adapter from the existing PSU leads to the 4-pin 12V
input socket on the motherboard. Actually with more modern
systems it is not only best but usually necessary, most
newer boards simply won't run at all without that 4 pin
connector receiving 12V directly.

Anyway I'd suspect the PSU as primary suspect, or if the
board had failed I would tend to blame the PSU for
contributing to it's demise and replace both... so you might
as well get a replacement PSU first if none of the above
seems to help.

Also try clearing CMOS, and check the battery voltage - some
boards won't post once the battery has drained too far
rather than just losing saved settings.
 
H

hot july

Thanks for the reply Kony. The PSU remains on, fans and HDD spin too. I just
thought the mobo used to beep when I turned it on. When I ran the old psu as
backup I disconnected all the hardware except the video card and hdd, so I
wasn't worried about power/wattage. Here is the psu I'm looking at now, and
I know I need at least a 430watter:

http://tinyurl.com/9qsd5

There is a 20+4 pin thing there, and I only need to the 20 pin. But I assume
that 4 xtra pin section will detach? yes?

The mobo is 478, and it's less than 5 years old, so I was hoping I wouldn't
have to worry about the cmos battery yet. I had already taken it out, and
pulled the cmos jumper on the mobo too just for the heck of it. I dont have
a clue how to check it for voltage as you suggested. But I know I got to
have a new psu even if I dont have to replace the mobo or cmos battery, so I
might as well order the psu and worry about the cmos thing later.
 
E

Ed Medlin

hot july said:
Thanks for the reply Kony. The PSU remains on, fans and HDD spin too. I
just thought the mobo used to beep when I turned it on. When I ran the old
psu as backup I disconnected all the hardware except the video card and
hdd, so I wasn't worried about power/wattage. Here is the psu I'm looking
at now, and I know I need at least a 430watter:

http://tinyurl.com/9qsd5

There is a 20+4 pin thing there, and I only need to the 20 pin. But I
assume that 4 xtra pin section will detach? yes?

The 4 pin connector on the main 20/24 pin main power connector is NOT the
same as the seperate 4 pin 12v connector although they look somewhat alike.
If the PSU is new enough to be a 20/24 pin, it should have the seperate 12v
connector too. It will fit correctly into the 4 pin connector on your MB and
get you going fine. I looked at the specs on that PSU and the rated 430w is
the MAX power not the actual running power of the unit. That means it is,
most likely, somewhere in the 350-375w range in actual running power. The
430w is misleading as it is actually just the startup power. It is good to
look at the actual specs of a PSU to make sure you are getting what you
need. Antec and PC Power and Cooling are two very good PSUs and others here
can help with other good PSU brands I am sure. It is not a good idea to
skimp on the PSU in any system as it is the heart of every system.


Ed
 
K

kony

The 4 pin connector on the main 20/24 pin main power connector is NOT the
same as the seperate 4 pin 12v connector although they look somewhat alike.
If the PSU is new enough to be a 20/24 pin, it should have the seperate 12v
connector too. It will fit correctly into the 4 pin connector on your MB and
get you going fine. I looked at the specs on that PSU and the rated 430w is
the MAX power not the actual running power of the unit. That means it is,
most likely, somewhere in the 350-375w range in actual running power. The
430w is misleading as it is actually just the startup power. It is good to
look at the actual specs of a PSU to make sure you are getting what you
need. Antec and PC Power and Cooling are two very good PSUs and others here
can help with other good PSU brands I am sure. It is not a good idea to
skimp on the PSU in any system as it is the heart of every system.


I agree, the current version of the Thermaltake that was
linked is a bit overrated, not equivalent to most name brand
430W PSU and has a mediocre fan, expected to have a shorter
life than many.
 
F

Fishface

hot said:
The PSU remains on, fans and HDD spin too. I just thought the
mobo used to beep when I turned it on. When I ran the old psu
as backup I disconnected all the hardware except the video card
and hdd, so I wasn't worried about power/wattage. Here is the
psu I'm looking at now, and I know I need at least a 430watter:

http://tinyurl.com/9qsd5

That power supply has a lot of happy owners.
If the 18A on the 12v rail is enough for your needs, that is mostly
what matters.

I purchased a previous incarnation of this unit which was
labelled at 420W but did not have the active PFC. Mine had
only a 20-pin connector, but it did include the P4 four-pin plug.
It also specified 18A on the 12V rail. I thought the connectors
were on the low-quality side (a little sloppy) when compared
with others I've owned, and it was a fairly loud. I had intended
to use it for my Abit NF-7, but ended up keeping the quieter
Enermax instead. It's back in the box, on the shelf, waiting for
someday.

There are also adapters which will supply power to the four-pin
P4 connector from a molex plug, such as this one on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290069135659

....that you may wish to try first.
 
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K

kony

That power supply has a lot of happy owners.
If the 18A on the 12v rail is enough for your needs, that is mostly
what matters.

I purchased a previous incarnation of this unit which was
labelled at 420W but did not have the active PFC. Mine had
only a 20-pin connector, but it did include the P4 four-pin plug.
It also specified 18A on the 12V rail. I thought the connectors
were on the low-quality side (a little sloppy) when compared
with others I've owned, and it was a fairly loud. I had intended
to use it for my Abit NF-7, but ended up keeping the quieter
Enermax instead. It's back in the box, on the shelf, waiting for
someday.


The older generation of Thermaltake you are thinking of is
probably not directly comparable- consider it coincidence
that it has the thermaltake label and similar wattage as it
is a completely separate design and IIRC, not even made by
the same company as the TR2 (Thermaltake doesn't make their
own). TR2 isn't a bad deal for the price, but not
comparable to most name brand 430W PSU.
 
F

Fishface

kony said:
The older generation of Thermaltake you are thinking of is
probably not directly comparable- consider it coincidence
that it has the thermaltake label and similar wattage as it
is a completely separate design and IIRC, not even made by
the same company as the TR2 (Thermaltake doesn't make
their own). TR2 isn't a bad deal for the price, but not
comparable to most name brand 430W PSU.

I shined a flashlight in mine. It doesn't look anything like the
one pictured in this article:
http://www.hardwaresecrets.com/article/332/1

They also say it is overrated at 430W and think 388W would
be more accurate (conclusion, last page).
 
K

kony

I shined a flashlight in mine. It doesn't look anything like the
one pictured in this article:
http://www.hardwaresecrets.com/article/332/1

They also say it is overrated at 430W and think 388W would
be more accurate (conclusion, last page).


Perhaps 388W at peak, not sustained output.
That PSU is better classified by price rather than what's on
the label. You can do worse, much worse with some generics
but it's not what I'd put in any system using more than
integrated video and basic 1 HDD, etc, configuration.
 
E

Ed Medlin

kony said:
Perhaps 388W at peak, not sustained output.
That PSU is better classified by price rather than what's on
the label. You can do worse, much worse with some generics
but it's not what I'd put in any system using more than
integrated video and basic 1 HDD, etc, configuration.

I put an OCC branded PSU in this system as it was locally available at a
friend's shop at a decent price. It actually lists the peak at 533w and
rated at 450w. It is a modular PSU and other than the very stiff 12v braided
power connectors (a bit tough to route and tie out of the way) it has served
me very well. I don't think OCC makes any PSUs either, but I haven't really
taken any time hunting down who makes theirs. I think it will take anything
I ever need to throw at it and it is very quiet.

Ed
 
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H

hot july

Hello everybody. Thank you for all the replies. As far as price goes, I can
actually beat the psu I linked in my earlier post:

http://tinyurl.com/2ygvn7


But right now I am looking to buy that adapter that Fishface told me about
on Ebay (
MH 4 Pin Molex to 4 Pin P4 Power Adapter
). Newegg doesnt have it. Does anyone know where else I can buy this adapter
from online other than Ebay?

http://tinyurl.com/ynq5pw

I actually have a 300watts psu so I would rather spend the $4-$6 on a 4 pin
converter to test the mobo, which I might have burned up, before I go and
buy a psu for this comp.

I got my back-up comp going, but it is 1.3ghz with 512mb ram and no-name
mobo whereas the other comp with asus mobo that I might have ruined is
2.4ghz with 1gig ram. But it's a 478 socket, so if I ruined the mobo, I'll
just be going to Sams to pick up a new comp instead of building my own again
:)

Thanks again guys.
 
P

Paul

hot said:
Hello everybody. Thank you for all the replies. As far as price goes, I can
actually beat the psu I linked in my earlier post:

http://tinyurl.com/2ygvn7


But right now I am looking to buy that adapter that Fishface told me about
on Ebay (
MH 4 Pin Molex to 4 Pin P4 Power Adapter
). Newegg doesnt have it. Does anyone know where else I can buy this adapter
from online other than Ebay?

http://tinyurl.com/ynq5pw

I actually have a 300watts psu so I would rather spend the $4-$6 on a 4 pin
converter to test the mobo, which I might have burned up, before I go and
buy a psu for this comp.

I got my back-up comp going, but it is 1.3ghz with 512mb ram and no-name
mobo whereas the other comp with asus mobo that I might have ruined is
2.4ghz with 1gig ram. But it's a 478 socket, so if I ruined the mobo, I'll
just be going to Sams to pick up a new comp instead of building my own again
:)

Thanks again guys.

This one is too much, at $10.00

http://www.cyberresearch.com/store/...rals/power-cords-cables/CBL_ATX12V_1802.5.htm

Same design, and $5.00

http://www.stayonline.com/detail.aspx?ID=1013

I was hoping to find one with two Molex connectors on one end
and the ATX12V on the other.

A nicer one here for $3.99. With this one, you don't lose the use
of your connectors.

http://www.censuspc.com/P4-Motherboard-To-ATX-Power-Supply-Y-Cable-12Inch-pr-540.html
http://www.censuspc.com/imagesProduct/d_327.gif

HTH,
Paul
 
H

hot july

Someone told me I might need to take the heat sink off the cpu and redo it's
thermal paste? What you think about that? I know about 4 months ago I did
take the heat sink off to clean it, but I did not redo the thermal paste
when I put it back on :(


http://tinyurl.com/2fdz2u

Ok, I ordered the adapter above. The thing is, the comp was working fine on
the psu without the 4-pin cable going to the cpu power connection on the
mobo. The psu works fine in my spare comp and so do all the other hardware
(monitor, video card, ram, etc). So I dont expect this new 4pin adapter to
make any difference, but it was just $10 so I am trying anyway. If the comp
still wont post after this step, I will post again to see how to go about
testing the mobo or cpu.

The mobo power light comes on so I thought if I had hurt the mobo by running
it without the 4-pin psu connector then that mobo power light would not be
on. I see no burn damage on any of the psu connectors or on the mobo pins.
That's also why I was thinking cpu was the culprit...........

Well, I'll let you know further late next week. cya guys!
 
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H

hot july

BTW, Kony asked about the model of the bakup psu earlier. In case any of you
are interested, the backup psu was an old E-Data atx300 with max output of
300 watts. I had already taken the top off and inspected inside. Nothing was
burned, and I had disconnected all the non essential comp hardware so that I
was just using this psu to power the agp4x video card, one hdd, one fan,
mobo, pentium 4 2.3ghz, and 1gig ram. Other than not having that cpu 4 pin
connector, this psu should have been ok for that--and it was for about 3
weeks :) After I started getting the "no signal" message, I also took out
the agp card so that I would just be using the onboard video.
 

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