JD said:
In the last couple of days, I posted a couple of questions about
noises emanating from my 15 month old WinXP computer, and I was
encouraged to make a ghost copy of my harddrive, which I did. Today,
I again had some difficulty booting up the computer (it did eventually
boot after about 8 tries), and this time I had the back of the
computer facing me. In that position, it was clear that the noise
coming from the computer was coming from the fan on the power source.
I have a new ATX power supply that I bought in case this turned out to
be the problem. My question is how do I go about replacing the old
power supply or the fan? Are there common mistakes or traps that I
should avoid. I would add that I have a standard desktop computer
case that is roughly 8 inches wide and 16 or 18 inches tall.
Any help would be appreciated.
Thanks,
JD
If you don't have a manual for the computer, then you want to make notes.
Or take digital pictures before hand. The connectors are keyed, by nature
of the shape of the nylon shells. So there isn't too much fear of plugging
them backwards or something. The floppy may have a different keying mechanism
than the others, and you may want to make a note of which wire color is on
the end pin, just in case.
There are several different power supply specs. The first one is from
when there was a 1x6 aux connector. The last two links may be more relevant.
The second link is for 20 pin main connectors. The third link shows the
current 24 pin main connector.
http://web.archive.org/web/20030424...org/developer/specs/atx/ATX_ATX12V_PS_1_1.pdf
http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf
http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf
What the documents don't show, is some of the tricks that the PSU makers
have used, to make their products cover a wider range of motherboards.
For example, if you read the last two docs above, you'll notice the
processor is powered by a 2x2 square connector. It will be near the processor
somewhere, because it feeds Vcore. When you look at some supplies, you'll
find a 2x4 pin connector. The 2x4 pin connector slides apart, into two 2x2
pieces. One of those pieces will be sufficient to plug into most current
desktop boards. In some cases, you might even find a 2x2 and a 2x4 connector,
on the same set of wires, and in that case, the either/or nature is easier
to understand.
On the 24 pin connectors, there is also the potential for a slider gadget.
The 24 pin can be split into a 20 pin section and a 4 pin section. The
20 pin section would be used for an older 20 pin motherboard. The 4 pin
section in that case, is a throwaway. Don't confuse the 4 pin throwaway
section, with the 4 pin that feeds the processor. The processor one has
two yellow and two black wires. The 4 pin throwaway section, has four
wires of different colors.
If your motherboard is 20 pin, and the PSU is 24 pin, and the PSU connector
does not slide apart, all is not lost. You can plug the 20 pin section into
the motherboard, leaving 4 pins hanging over the end. If there are physical
components in the way, only then do you go out and buy an adapter cable.
From that, you can see the value of the splittable 24 pin connector.
If the motherboard has a 24 pin connector, and the power supply has a 20 pin,
again, don't panic. The 20 pin can be aligned with one end of the 24 pin
motherboard connector, and plugged in. The only time you really need a 24 pin
connector, for a 24 pin motherboard, is if the computer has SLI or Crossfire
video cards (two PCI Express cards in the two video slots).
The next part of your analysis, is how many cables did the old supply have,
and how many cables does the new one have. If the new one has fewer cables
for hard drives or optical drives, or if the new supply has a mix of SATA and
the older 1x4 Molex drive power connectors, you may need to purchase additional
"Y cables" to finish the job.
Other rules of thumb - if the video card has a 1x4 Molex on the end, if you
have the cables to spare, you feed a unique cable to that one. That is in
case the video card uses a lot of power. For example, my card draws 5.5 amps
on the 5V rail (a bit unusual), and while the cable can probably carry 8 or
10 amps, I don't push it. So the cable that runs the video card, isn't being
used to also power any hard drives. If you are low on cables, and in a hurry,
you can always use that cable for more than one thing, but watch the performance
of the computer, to see whether it is really happy that way or not.
So, do your planning. Count the number of cables. Figure out how best to route
the disk drive cables. My computer has an upper and lower drives section, and
one power cable does the upper section, and another one does the lower drive
bays.
Your power supply could have modular cables, in which case you only plug in the
ones you need. For permanently attached cables, you can keep elastics or nylon
tie wraps, around the unused cables. That helps keep them out of the way.
You can also do simple stuff, like comparing the dimensions of the old and
new supply. No sense ripping the old one out, if the new one isn't going to
fit. Some pre-built computers are pretty small, and may use a microATX
supplu. Also, some of the monster supplies (>650W or so), may be an inch
or two longer than normal. The width and height will be normal, but the
length is variable.
Also, check the position of the screw holes, and fan aperture on the computer
case. Sometimes, the new supply won't fit snug against the back wall, because
the two don't seem to agree. Occasionally, you'll read a story where someone
finds the screw holes don't line up, or the orientation of the fan is upside-down.
There should be a fan-hole that points towards where the CPU is located, the
idea being, that the PSU pulls hot air away from the CPU, and sends it out the
back of the power supply and into the room.
Any time you make notes about your computer, you can keep them inside the
computer case. That makes them harder to lose.
Depending on how many disk drives you have, and if they all have exactly
the same capacity, you can use a label maker, to make descriptive labels
for them. I have one with "FreeBSD" on the back, one with "Win2K + ATI
driver" and so on. (I have a spare drive with "Win2K + Nvidia driver" too.)
If you label the drive, each time you install a new one, it is easier
later when the drive fails, to physically remove the correct one. I don't
change the contents and layout of the drives enough, to need to change the
label. (I just buy a new drive
)
HTH,
Paul
