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March 16, 2006, 7:31 pm
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work. Iíve upgraded to 2gb of RAM, and an 256mb 8x graphics
card. It basically
stays on all the time, I do reboot it daily
though. The problem I have is that
occasionally, it will randomly
reboot. When doing so it pauses at a certain
point and throws up an
error message saying that it cannot find the hard drive.
here, until I come home from work and see that it has been sitting in
this state for the better part of the day. I reboot, and usually it
On special occasions, however, upon the reboot it will
get all the to the
ďwelcomeĒ screen, then reboot constantly until I
power it off. When I power it
off and allow it to rest for 20-30
minutes, it boots and acts normal.
sending this verbatim description to www.frozencpu.com, they
informed me that
this sounds like a psu issue, which i'm fine with.
My question that they, or
anyone could not answer is this; I know
nothing about psu and cpu fans or any
kind of cooling what have you.
I could not find any info on what is compatible
with my cpu, or what
to stay away from. I need direction!
Re: eMachine T4010 power supply
Emachines has a parts web page. The T4010 takes me here.
You can shop for a power supply, by comparing the spec on the label
on the side of the supply, to the lists on a web site. The replacement
supply should have greater than or equal to "amps" for each output
supply voltage. There will be a number of amps listed for the 3.3V,
the 5V, the 12V and so on. You also need something having the same
physical dimensions, in case the original is some kind of smaller
form factor supply.
As far as cooling goes, an Intel retail CPU comes with a heatsink
and fan, so in that case there is nothing to work out. People who
replace their heatsink and fan as a unit, get a performance number
(theta_R, the thermal resistance). Basically that unit of merit,
relates degrees C of temperature rise, to the Watts of heat spit out
by the CPU.
To work an example, say the room temp is 25C, the air inside the
case is 32C (if it is cooled well). We want to keep the CPU
under 60C (or whatever your target max temperature is). From the
processorfinder web page, your processor TDP power is 84W.
(60C-32C)/84W = 0.33C/W . A lower number is better performance,
and our combo fan plus the heatsink should give us better than
On a hot day, the room temp and case air temp rise (especially
if the room is not air conditioned). In which case, the theta_R
has to drop a bit (cool better).
Now, let us compare two cooling products. One is "silent" while
the other one is for deaf people or Ipod owners :-)
Both of them use heatsinks that are reasonably similar in shape
and capability. That leaves the fan to distinguish the
performance. The specs:
27.5 CFM 21 dBA Rated Current 0.13A (from graph, theta_R = 0.50C/W)
72.9 CFM 48 dBA Rated Current 0.45A (from graph, theta_R = 0.20C/W)
Those fans are 80mm x 80mm. A fan spec somewhere between those
two sounds like it might work.
The Intel retail fan usually has a built-in thermal sensor, and
it measures air temperature. That allows the Intel fan to speed
up when the air temperature in the case rises. The fan is
temperature sensitive in that case.
Your replacement fan should have the same number of pins, to
match the header on the motherboard. Recently shipping processors
use a four pin fan header. The pins are GND, +12V, RPM_signal,
and PWM_control. If the RPM_signal is missing, some BIOS respond
by shutting the computer off a few seconds into POST (so using
a cheap computer case cooling fan, that has only two wires, might not
work). The PWM_control is optional, and allows the BIOS or the system
software, to also have a say about fan speed. A three pin fan
header, won't have PWM_Control, leaving the case air temperature
sensing feature as the only automatic way of speed adjustment.
But it will still work. It is also possible to use a three wire
fan, and a separate fan speed control knob, such as a Zalman
FanmateII to set the speed of the fan, as desired, for best
balance between necessary cooling and noise. When summer comes,
you turn up the knob, while in winter you can turn it down.
So, your replacement fan should have a minimum of three wires,
and a three or four pin connector that mates with the pin header
on the motherboard. (A three pin can be connected to a four pin
header, just be careful to get the orientation correct.) You can
open the case and examine what is already present, before shopping
for a new one. You want a fan with enough CFMs to give a good
enough theta_R to keep the processor temperature reasonable.
At 70C, the processor automatically reduces its computing rate,
so you want to stay below the 65C-70C range. As a result, I
picked 60C target temperature in my example above.
There is a curve here, that shows how theta_R changes with
RPMs. Ideally, we'd want to see the units on this curve,
in CFM, to make it easier to select a fan. Maybe about
45CFM would be enough, plus a FanMateII to adjust for noise
(most of the time, we don't need all of the 45CFM). Just
a guess on my part.
Normally, people buy an aftermarket heatsink plus fan together,
so that takes the guesswork out of figuring out what the
resulting theta_R will be, but it shouldn't take more than
two fan purchases, for you to get in the right ballpark :-)
Make sure the fan you buy has ball bearings, and if the
bearing type is not stated, it will be a sleeve bearing fan.
(Only the sealed Panaflo sleeve bearing fans are worth buying,
if you go for a sleeve bearing fan. The rest use an open
bearing that won't last very long.)
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