Power supply hot to touch

On Sun, 2 Mar 2008 19:17:47 -0500, "Skeleton Man"
<invalid@guestwho.com> wrote:

>Hi All,
>
>I just took the side of my case to improve CPU temps and noticed two things:
>
>1) The PSU is very hot. I mean to the point of burning your hand almost (as
>is the exhaust air from the back).

Either:

A) It's junk and will fail soon
B) The fan and/or case intake isn't adequate for the load.


>2) I think the fan on the bottom is blowing hot air into the case, not out.

?? If it has adequate exhaust area, that shouldn't be an
issue.


>
>Removing the side dropped CPU and both core temps by about 10C. I only have
>one 120mm exhaunst fan and the same at the front for intake (I don't think
>either of these work very well - I can hardly feel any air move past them).

This suggests the case itself impedes airflow, but it
doesn't necessarily mean the PSU is of acceptible quality or
capacity.


>
>Now as for the PSU, this worries me because I'm used to it being a little
>warm, but not hot like this. It's a Dynex 500W (specs below), my old blew
>and this is the only brand Bestbuy carries (nearest place to get a PSU same
>day). For the longest time I thought both fans on the PSU were blowing
>outwards (bottom one sucking hot air from the case and the rear one blowing
>it out).

I would not carry any confidence at all on only what bestbuy
carried. There are ample PSU reviews online, if you can
take that PSU back for refund that seems the best option.


>
>If the PSU is blowing more hot air into the case, it's likely why my CPU
>temps are high - the fan is right over the hsf for the cpu.
>
>PSU specs:
>--------------------------------------------------------------------------
>Voltage: +3.3V +5V +12V1 +12V2 -5V -12V +5Vsb
>Max Load: 35A 40A 16A 18A 0.5A 0.8A 2.5A
>Min load: 0.5A 2.0A 1.0A 1.0A 0A 0A 0A
>Regulations: ±5% ±5% ±5% ±10% ±10% ±5%
>Ripple: 50mV 50mV 120mV 120mV 100mV 120mV 50mV
>Noise & Ripple 100mV 100mV 200mV 200mV 200mV 200mv 100mv
>Fan Speed Control Inside
>--------------------------------------------------------------------------
>
>My setup:
>---------------------------------------------------------------
>M/B: MSI K9N4SLI
>CPU: Athlon 64 X2 5200+ (2600Mhz, 13 x 200, stock values)
>RAM: 2x 512MB Kingston HyperX DDR2 800Mhz
>Gfx: PCI-E RADEON X1600
>HDD1: Western Digital WD800JB PATA 7200RPM
>HDD2: Western Digital WD2000JB PATA 7200RPM
>DVD: Sony/Optiarc AD5170A DVDRW
>
>Vcore: 1.3v (stock voltage - it won't run below this)
>RAM: 1.95v (again, stock voltage)
>--------------------------------------------------------------
>
>Given the specs above, is it likely the PSU is cheaply built and being run
>to capacity ? (hence the heat)

The heat is a function of fan speed, when considering
external PSU case temp, but it is also likely it's cheap
junk and should be replaced.

Hi All,

I just took the side of my case to improve CPU temps and noticed two things:

1) The PSU is very hot. I mean to the point of burning your hand almost (as
is the exhaust air from the back).
2) I think the fan on the bottom is blowing hot air into the case, not out.

Removing the side dropped CPU and both core temps by about 10C. I only have
one 120mm exhaunst fan and the same at the front for intake (I don't think
either of these work very well - I can hardly feel any air move past them).

Now as for the PSU, this worries me because I'm used to it being a little
warm, but not hot like this. It's a Dynex 500W (specs below), my old blew
and this is the only brand Bestbuy carries (nearest place to get a PSU same
day). For the longest time I thought both fans on the PSU were blowing
outwards (bottom one sucking hot air from the case and the rear one blowing
it out).

If the PSU is blowing more hot air into the case, it's likely why my CPU
temps are high - the fan is right over the hsf for the cpu.

PSU specs:
--------------------------------------------------------------------------
Voltage: +3.3V +5V +12V1 +12V2 -5V -12V +5Vsb
Max Load: 35A 40A 16A 18A 0.5A 0.8A 2.5A
Min load: 0.5A 2.0A 1.0A 1.0A 0A 0A 0A
Regulations: ±5% ±5% ±5% ±10% ±10% ±5%
Ripple: 50mV 50mV 120mV 120mV 100mV 120mV 50mV
Noise & Ripple 100mV 100mV 200mV 200mV 200mV 200mv 100mv
Fan Speed Control Inside
--------------------------------------------------------------------------

My setup:
---------------------------------------------------------------
M/B: MSI K9N4SLI
CPU: Athlon 64 X2 5200+ (2600Mhz, 13 x 200, stock values)
RAM: 2x 512MB Kingston HyperX DDR2 800Mhz
Gfx: PCI-E RADEON X1600
HDD1: Western Digital WD800JB PATA 7200RPM
HDD2: Western Digital WD2000JB PATA 7200RPM
DVD: Sony/Optiarc AD5170A DVDRW

Vcore: 1.3v (stock voltage - it won't run below this)
RAM: 1.95v (again, stock voltage)
--------------------------------------------------------------

Given the specs above, is it likely the PSU is cheaply built and being run
to capacity ? (hence the heat)

Chris

One thing I just noticed doing some math - how can you get 724W of power
from a PSU rated for 500W ?

3.3V x 35A = 116W
5.0V x 40A = 200W
12.0V x 16A = 192W
12.0V x 18A = 216W
-----------------------
Total: 724W

Am I calculating something wrong ?

Chris

"Skeleton Man" <invalid@guestwho.com> wrote in message
news:yLmdnZVwA_Xg21banZ2dnUVZ_qSonZ2d@wightman.ca...
> One thing I just noticed doing some math - how can you get 724W of power
> from a PSU rated for 500W ?
>
> 3.3V x 35A = 116W
> 5.0V x 40A = 200W
> 12.0V x 16A = 192W
> 12.0V x 18A = 216W
> -----------------------
> Total: 724W
>
> Am I calculating something wrong ?
>
> Chris
>
>
Those are the maximums each rail can supply. In the specs it usually
states what specific combinations can supply. It's very unlikely the
3.3V or 5.0V demands will be anywhere near the PSU capabilities.
The important spec these days is for the 12V rails as they power the CPU
and video card(s).

The specs are for each voltage when it is running alone. E.g. if you are using only 3.3 volts it will put out 116 watts and if you are using only 5 volts it will put out 200 watts, but the combined output of 5 volts and 3.3 volts together might be only 220 watts. Also the ratings will vary depending on if the rating is for peak power when cold or continuous power when hot.

Skeleton Man wrote:
>
> One thing I just noticed doing some math - how can you get 724W of power
> from a PSU rated for 500W ?
>
> 3.3V x 35A = 116W
> 5.0V x 40A = 200W
> 12.0V x 16A = 192W
> 12.0V x 18A = 216W
> -----------------------
> Total: 724W
>
> Am I calculating something wrong ?
>
> Chris

--
Mike Walsh

Skeleton Man wrote:
> Hi All,
>
> I just took the side of my case to improve CPU temps and noticed two things:
>
> 1) The PSU is very hot. I mean to the point of burning your hand almost (as
> is the exhaust air from the back).
> 2) I think the fan on the bottom is blowing hot air into the case, not out.
>
> Removing the side dropped CPU and both core temps by about 10C. I only have
> one 120mm exhaunst fan and the same at the front for intake (I don't think
> either of these work very well - I can hardly feel any air move past them).
>
> Now as for the PSU, this worries me because I'm used to it being a little
> warm, but not hot like this. It's a Dynex 500W (specs below), my old blew
> and this is the only brand Bestbuy carries (nearest place to get a PSU same
> day). For the longest time I thought both fans on the PSU were blowing
> outwards (bottom one sucking hot air from the case and the rear one blowing
> it out).
>
> If the PSU is blowing more hot air into the case, it's likely why my CPU
> temps are high - the fan is right over the hsf for the cpu.
>
> PSU specs:
> --------------------------------------------------------------------------
> Voltage: +3.3V +5V +12V1 +12V2 -5V -12V +5Vsb
> Max Load: 35A 40A 16A 18A 0.5A 0.8A 2.5A
> Min load: 0.5A 2.0A 1.0A 1.0A 0A 0A 0A
> Regulations: ±5% ±5% ±5% ±10% ±10% ±5%
> Ripple: 50mV 50mV 120mV 120mV 100mV 120mV 50mV
> Noise & Ripple 100mV 100mV 200mV 200mV 200mV 200mv 100mv
> Fan Speed Control Inside
> --------------------------------------------------------------------------
>
> My setup:
> ---------------------------------------------------------------
> M/B: MSI K9N4SLI
> CPU: Athlon 64 X2 5200+ (2600Mhz, 13 x 200, stock values)
> RAM: 2x 512MB Kingston HyperX DDR2 800Mhz
> Gfx: PCI-E RADEON X1600
> HDD1: Western Digital WD800JB PATA 7200RPM
> HDD2: Western Digital WD2000JB PATA 7200RPM
> DVD: Sony/Optiarc AD5170A DVDRW
>
> Vcore: 1.3v (stock voltage - it won't run below this)
> RAM: 1.95v (again, stock voltage)
> --------------------------------------------------------------
>
> Given the specs above, is it likely the PSU is cheaply built and being run
> to capacity ? (hence the heat)
>
> Chris
>

Some interpretations:

1) Your previous power supply blew. Perhaps the motherboard was overloading it.
The motherboard could be overloading the current supply.

2) The supply is getting hot, because of a fault within the supply
itself. There could be a short in there somewhere.

3) The power supply fan has stopped turning.

For (1), I would use the clamp-on DC ammeter I own, to measure
all rails, and see if excessive motherboard current draw is
present. Because the clamp-on meter is a non-contact device,
it can measure and characterize a computer rapidly, without
the need to snip wires.

For (3) you can check visually, as well as audibly. If the
fan slowed down, perhaps you remember it running faster at one
time.

For (2), that would be harder to check. I might disconnect the supply
from the motherboard, plug it into a Kill-a-Watt meter, and see
if the unloaded dissipation is in the 10W to 20W region or not,
with PS_ON# connected to COM.

In other words, if you really want to know what is going on,
it'll take a bit of test equipment. Slapping new power supplies
in there, over and over again, may not fix it.

A Kill-a-Watt meter is cheap, and is worthwhile to have around the
house. The clamp-on DC ammeter is much more expensive.

http://ecx.images-amazon.com/images...VAL._AA183_.jpg
http://www.amazon.com/P3-Internatio...r/dp/B00009MDBU

Paul

On Mar 2, 7:34 pm, "Skeleton Man" <inva...@guestwho.com> wrote:
> One thing I just noticed doing some math - how can you get 724W of power
> from a PSU rated for 500W ?

You are already doing more than most manufacturers intend. Most
computer assemblers who buy power supplies look only two numbers:
watts and dollars. So many power supplies are marketed to people who
would not do numbers.

ATX specs note that one voltage may output a maximum amperage only
when the other voltage load is much smaller. Charts even exist for
these relationships.

Did excessive loading cause an old supply to fail? Maybe if the
supply was defective when purchased. For any properly designed supply
- no load can damage the supply. In fact, every supply can have
shorted together all outputs without any supply damage. Some specs
even define how large that wire must be to short together all outputs
- without damage. Power supply must provide any load or shutdown.
Damage is not listed among the possibilities - if a supply is properly
designed.

How much was that new supply? One benchmark; if less than $60 full
retail, then is probably missing essential functions. Obviously the
reverse is not true: that a $60 power supply is sufficient.

Did that supply come with a long list of numeric specs that list its
many required functions? Better supplies will claim to provide those
required functions - in writing. If not, then assume some required
functions are missing. Normal is a computer booting when a supply is
defective. You can identify a bad supply but cannot 'see' a good one.
Latter requires a simple tool.

One chassis fan should be sufficient cooling for any computer even
operating in a normal 100 degree F environment. No, that is not
normal for you but must be normal for any computer. Does not matter
which direction fans blow. Relevant factor is air flow - the number
of CFMs that move through a chassis. Obviously if both 120 mm fans
blow in and no other exhaust is available, then number of CFMs can be
reduced.

That is chassis temperature - not to be confused with your other
objective - CPU temperatures. CPU temperature analysis starts with a
spec for that heatsink fan combo - degree C per watt. What does that
manufacturers state in writing?

Power supply should typically work without a fan in a 70 degree F
room. Then we push air through with a fan to make supply even more
robust, so that it will work at room temperatures above 100 degree F,
AND to move sufficient air through the chassis. Same fan solved two
problems. Some supplies are not so robust. But appreciate an old
rule for all semiconductors. If you touch it and don't leave skin,
then it is not too hot.

Still, prefer your power supply case to be less than 100 degrees F
when in a 70 degree room because doing that is so easy. How hot is
that power supply box - in numbers? How much air is really moving
through the chassis (do fans operate in series or are they 'fighting'
each other)?

"kony" <spam@spam.com> wrote in message
news24ks3lj6qggb86fevh8qpe7188plbnkoh@4ax.com...
> On Sun, 2 Mar 2008 19:17:47 -0500, "Skeleton Man"
> <invalid@guestwho.com> wrote:
>
>>Hi All,
>>
>>I just took the side of my case to improve CPU temps and noticed two
>>things:
>>
>>1) The PSU is very hot. I mean to the point of burning your hand almost
>>(as
>>is the exhaust air from the back).
>
> Either:
>
> A) It's junk and will fail soon
> B) The fan and/or case intake isn't adequate for the load.
>
>
>>2) I think the fan on the bottom is blowing hot air into the case, not
>>out.
>
> ?? If it has adequate exhaust area, that shouldn't be an
> issue.
>

So you see no problem with a PSU that has fans blowing air
out, but no way for much air to go into the PSU? Personally,
I would think competing fans might actually make the PSU
hotter.


>
>>
>>Removing the side dropped CPU and both core temps by about 10C. I only
>>have
>>one 120mm exhaunst fan and the same at the front for intake (I don't think
>>either of these work very well - I can hardly feel any air move past
>>them).
>
> This suggests the case itself impedes airflow, but it
> doesn't necessarily mean the PSU is of acceptible quality or
> capacity.
>

True, at least in the since that the hot air from the PSU
had no place to go , but onto the CPU heat sink, with the
side on. With the side off, there would be a path that allows
it to flow, and even hot air can carry away heat, if it is
moving air.

>
>>
>>Now as for the PSU, this worries me because I'm used to it being a little
>>warm, but not hot like this. It's a Dynex 500W (specs below), my old blew
>>and this is the only brand Bestbuy carries (nearest place to get a PSU
>>same
>>day). For the longest time I thought both fans on the PSU were blowing
>>outwards (bottom one sucking hot air from the case and the rear one
>>blowing
>>it out).
>
> I would not carry any confidence at all on only what bestbuy
> carried. There are ample PSU reviews online, if you can
> take that PSU back for refund that seems the best option.
>
>
>>
>>If the PSU is blowing more hot air into the case, it's likely why my CPU
>>temps are high - the fan is right over the hsf for the cpu.
>>
>>PSU specs:
>>--------------------------------------------------------------------------
>>Voltage: +3.3V +5V +12V1 +12V2 -5V -12V +5Vsb
>>Max Load: 35A 40A 16A 18A 0.5A 0.8A 2.5A
>>Min load: 0.5A 2.0A 1.0A 1.0A 0A 0A 0A
>>Regulations: ±5% ±5% ±5% ±10% ±10% ±5%
>>Ripple: 50mV 50mV 120mV 120mV 100mV 120mV 50mV
>>Noise & Ripple 100mV 100mV 200mV 200mV 200mV 200mv 100mv
>>Fan Speed Control Inside
>>--------------------------------------------------------------------------
>>
>>My setup:
>>---------------------------------------------------------------
>>M/B: MSI K9N4SLI
>>CPU: Athlon 64 X2 5200+ (2600Mhz, 13 x 200, stock values)
>>RAM: 2x 512MB Kingston HyperX DDR2 800Mhz
>>Gfx: PCI-E RADEON X1600
>>HDD1: Western Digital WD800JB PATA 7200RPM
>>HDD2: Western Digital WD2000JB PATA 7200RPM
>>DVD: Sony/Optiarc AD5170A DVDRW
>>
>>Vcore: 1.3v (stock voltage - it won't run below this)
>>RAM: 1.95v (again, stock voltage)
>>--------------------------------------------------------------
>>
>>Given the specs above, is it likely the PSU is cheaply built and being run
>>to capacity ? (hence the heat)
>
> The heat is a function of fan speed, when considering
> external PSU case temp, but it is also likely it's cheap
> junk and should be replaced.

How about: it's a function of the air flow through the
PSU case? If you have a box with competing fans;
where both are trying to blow air in or trying to blow
the air out, you aren't going to have much air flow. The
best practice, with multiple fans, is to have intake fans in
one corner of the box and the exhaust fans in the opposite
corner, so the air flows through the whole box. Since
hot air rises, it is natural to have the intake at or near the
bottom and the exhaust at or near the top.

But you knew that, didn't you, Kony?

Luck;
Ken

Skeleton Man wrote:
> Hi All,
>
> I just took the side of my case to improve CPU temps and noticed two things:
>
> 1) The PSU is very hot. I mean to the point of burning your hand almost (as
> is the exhaust air from the back).
> 2) I think the fan on the bottom is blowing hot air into the case, not out.
>
> Removing the side dropped CPU and both core temps by about 10C. I only have
> one 120mm exhaunst fan and the same at the front for intake (I don't think
> either of these work very well - I can hardly feel any air move past them).
>
> Now as for the PSU, this worries me because I'm used to it being a little
> warm, but not hot like this. It's a Dynex 500W (specs below), my old blew
> and this is the only brand Bestbuy carries (nearest place to get a PSU same
> day). For the longest time I thought both fans on the PSU were blowing
> outwards (bottom one sucking hot air from the case and the rear one blowing
> it out).
>
> If the PSU is blowing more hot air into the case, it's likely why my CPU
> temps are high - the fan is right over the hsf for the cpu.
>
> PSU specs:
> --------------------------------------------------------------------------
> Voltage: +3.3V +5V +12V1 +12V2 -5V -12V +5Vsb
> Max Load: 35A 40A 16A 18A 0.5A 0.8A 2.5A
> Min load: 0.5A 2.0A 1.0A 1.0A 0A 0A 0A
> Regulations: ±5% ±5% ±5% ±10% ±10% ±5%
> Ripple: 50mV 50mV 120mV 120mV 100mV 120mV 50mV
> Noise & Ripple 100mV 100mV 200mV 200mV 200mV 200mv 100mv
> Fan Speed Control Inside
> --------------------------------------------------------------------------
>
> My setup:
> ---------------------------------------------------------------
> M/B: MSI K9N4SLI
> CPU: Athlon 64 X2 5200+ (2600Mhz, 13 x 200, stock values)
> RAM: 2x 512MB Kingston HyperX DDR2 800Mhz
> Gfx: PCI-E RADEON X1600
> HDD1: Western Digital WD800JB PATA 7200RPM
> HDD2: Western Digital WD2000JB PATA 7200RPM
> DVD: Sony/Optiarc AD5170A DVDRW
>
> Vcore: 1.3v (stock voltage - it won't run below this)
> RAM: 1.95v (again, stock voltage)
> --------------------------------------------------------------
>
> Given the specs above, is it likely the PSU is cheaply built and being run
> to capacity ? (hence the heat)
>
> Chris
>
>

I have no doubt that the PSU is cheaply built. Had you ever heard of
Dynex before you wandered into BestBuy?

But even a cheap PSU wouldn't be expected to blow hot air from its
bottom fan into the computer case -- it definitely should be sucking air
from above the CPU and ejecting it out the rear of the case.. Could be
that one of the assembly line workers was having an especially bad day
and inserted it backwards...

--
John McGaw
[Knoxville, TN, USA]
http://johnmcgaw.com

On Mar 3, 3:51 pm, John McGaw <nob...@nowh.ere> wrote:
> But even a cheap PSU wouldn't be expected to blow hot air from its
> bottom fan into the computer case -- it definitely should be sucking air
> from above the CPU and ejecting it out the rear of the case.

First, the original ATX specs called for blowing air into the case
from power supply. Later, that standard changed; reversed airflow.

Second, relevant number is CFM through the chassis. Basic science
(read application notes from fan manufacturers) makes it obvious.
Relevant to chassis internal temperatures is the parameter called CFM
and temperature where air enters the chassis.

One standard 80 mm or 120 mm fan provides more than enough airflow
even assuming no heat gets transferred through a metal chassis.
Second fan (if in parallel) provides only a marginal temperature
improvement. But it two fans are blowing in so as to reduce the
total CFMs, then a problem has been created. Simplest answer for
chassis cooling starts with these numbers. How many CFM are being
moved through that chassis? Airflow direction is irrelevant. CFMs are
relevant.


Meanwhile, as others noted, that power supply should not be hot to
touch. Hot? How hot? How many have assumed 130 degrees F or
higher? Without numbers, everyone must speculate.