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Low 12 volts rail?

B

BigDaddy85

Gawd
Joined
May 13, 2005
Messages
876
The title say it all. Anyways, I am experiencin an average of 11 volts on my dad's hp puter with 250 watts psu. Everytime I boot up my dad's pc, the fan runnin very fast at the start then adjusted itself to lower speed like 40% or less, and I couldn't feel any air out of the rear. I had to use Speed Fan program to raise the fan into full speed. Funny thing is that it's runnin very stable. :confused:

My question is does the 12 volt rail is not givin enuf power to the sys and cause the fan to run very low at normal operation?

If so, then would u recommend me to buy new psu?
 
BigDaddy85 said:
The title say it all. Anyways, I am experiencin an average of 11 volts on my dad's hp puter with 250 watts psu. Everytime I boot up my dad's pc, the fan runnin very fast at the start then adjusted itself to lower speed like 40% or less, and I couldn't feel any air out of the rear. I had to use Speed Fan program to raise the fan into full speed. Funny thing is that it's runnin very stable. :confused:

My question is does the 12 volt rail is not givin enuf power to the sys and cause the fan to run very low at normal operation?

If so, then would u recommend me to buy new psu?
Click to expand...

How do you know it is low? Did you check it with a voltmeter? If it were 11v's it would be waaaaaayyyyyy out of spec and not stable.
 
BigDaddy85 said:
Everest indicated this silly voltage.
Click to expand...
Silly software. :p

Check it with a multimeter if you are really concerned but if it is running stable the 12v isn't at 11v.
 
well i don't have voltmeter at all. Y would the fan run very low at the boot up even durin the normal operation without tweakin the fan with speed fan program?

Also speed fan said it's at 11 volt too.

Edit: two screenshots

and
 
Sounds like the fan is working normally and is being temp controlled.
 
well the temperature isn't good at all. I went to bios and it said 55C with low speed fan. Durin the window operation, I tweaked the fan to full speed and waited a little bit. After that, I touched the heatsink and it feel cool with full speed fan. Also I need to mention this that it feels so hot to touch with low speed fan (before tweak). The program isn't accurate at all so I agreed with the bios sensor though. :(

I am kinda thinkin mobo is defective or the psu isn't performin well. The cpu is 3000+ barton @ 400 fsb.
 
All the onboard software should agree with the BIOS sensor because that is where it get's the voltage reading from. As for the fan what heatsink are you touching?
 
the bottom part of heatsink, also it's aluminum with small circle copper that touchin processor only.
 
BigDaddy85 said:
the bottom part of heatsink, also it's aluminum with copper base on it.
Click to expand...
So the CPU heatsink...not the northbridge?

Is the heatsink/fan dusty?
 
no it's clean also there's passive heatsink on NB chipset.

Edit: I am gonna reboot and check the voltage on bios.
 
Ok then with a 12v regulated processor and it is stable at the reported voltage of 11v's I am seriously thinking it is not a PSU issue as that is pretty far out of spec to still be stable. I would guess the snesor is not functioning properly.
 
dang it so should i get new mobo instead?

Edit: Also bios didn't say anything bout volt expect temperature and fan sensor.
 
BigDaddy85 said:
dang it so should i get new mobo instead?

Edit: Also bios didn't say anything bout volt expect temperature and fan sensor.
Click to expand...

Is it still covered by HP's warranty?
 
BigDaddy85 said:
I had no idea, let me ask my dad also he bought it from wal-mart (jeez lol).
Click to expand...

Ok. If it isn't though.........and it is working fine otherwise I really wouldn't mess with it. It sounds like it is working within spec.
 
1 yr warranty, but it already expired just by few months. I am not happy with this silly system btw, prolly i should get new fan that blow better with moltex connector or buy 3 pin to 4 pin adapter.

Anyways, thx u for helpin me out. :)
 
Ok, what the fuck... After seeing BigDaddy's HP computer having 11.07v on the 12v rail and having low RPM on the CPU and exhaust fans at startup, I decided to see if my mom's HP Pavilion a710e had the same thing. YES! It's got the exactly same fucking thing. Downloaded SpeedFan 4.25, and saw that both fans were at 40%. Now I feel hot air coming out of the case. Plus Everest and Speedfan says that the 12v rail is 11.08v. WTF?!
 
Mr. Stryker said:
Ok, what the fuck... After seeing BigDaddy's HP computer having 11.07v on the 12v rail and having low RPM on the CPU and exhaust fans at startup, I decided to see if my mom's HP Pavilion a710e had the same thing. YES! It's got the exactly same fucking thing. Downloaded SpeedFan 4.25, and saw that both fans were at 40%. Now I feel hot air coming out of the case. Plus Everest and Speedfan says that the 12v rail is 11.08v. WTF?!
Click to expand...

Well that just makes me think more of the same in that the problem is sensor's/software not the PSU and the hardware is working within spec.
 
o well i think i am gonna teach my dad how to tweak the fan lol. :D

man i am gonna get him venice system with 3000+ in near future. I am sick of oem puter btw, and my dad wasn't bein very patient with the puter stuff. o well lol
 
This actually sounds entirely normal. Most OEM systems use some sort of fan control in order to keep noise down. Most PC owners aren't happy with cranked up fans. It's probable that HP is using a chip that monitors the CPU temp and then adjusts the fan speeds to keep the CPU just inside of spec. It should speed up the fans as the workload goes up. CPU fan wil likely be the first one to speed up, then the chassis fans.

The voltage also seems normal. ATX spec allows +/- 5% on the rails and the monitor chip probably has an error of +/- 3%. Add up all that error and the voltage could read as low as 11.058V. It also makes sense that HP PSU's would run on the lower side of the spec. It's cheaper, and since 12V is regulated down to lower voltages on the board, the supply voltage can droop without much problem, as long as the onboard regulators are adjusted to accept it.
 
breetai72 said:
It also makes sense that HP PSU's would run on the lower side of the spec. It's cheaper, and since 12V is regulated down to lower voltages on the board, the supply voltage can droop without much problem, as long as the onboard regulators are adjusted to accept it.
Click to expand...

So how exactly is it cheaper to contract out PSU's with lower 12v again?
 
A tighter tolerance (i.e. 12V +/- 1%) needs more expensive resistors, caps, controllers, etc. in order to maintain the tolerance. These can be significantly more expensive. It might also mean more expensive FETs depending on how the VR is designed.

It's cheaper to design to a looser tolerance. If HP figured they could tolerate +/- 10% instead of +/-5% they can certainly ask their PSU vendor to accomodate. After all, the system isn't intended to be upgraded and make use of mass market device.
 
breetai72 said:
A tighter tolerance (i.e. 12V +/- 1%) needs more expensive resistors, caps, controllers, etc. in order to maintain the tolerance. These can be significantly more expensive. It might also mean more expensive FETs depending on how the VR is designed.

It's cheaper to design to a looser tolerance. If HP figured they could tolerate +/- 10% instead of +/-5% they can certainly ask their PSU vendor to accomodate. After all, the system isn't intended to be upgraded and make use of mass market device.
Click to expand...

So then your agruement is nonspec compliance not lower voltage. That is different.
 
I'm not sure what you mean by argument. I'm just saying that the low voltage isn't necessarily a bad thing. In fact it could be by design on the OEM's part.

As an aside, a low voltage isn't always bad anyway. As long as the rail can support the current demanded of it, a low (but within spec) voltage is fine. The assumption most make is that a low voltage indicates a lack of regulation. However, since a CPU VR is regulating the voltage down from 12V to 1.5 or less the voltage isn't the chief concern. The current is. A low voltage can indicate that the current load is too high, causing the regulator to droop the voltage, but it's not always the case.
 
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