Hi, I'm not a techie but I'm trying to change a power supply in a Desktop PC and it all looks quite straightforward. I'm making sure I'm putting all the leads in the right place by following EXACTLY the where the leads for previous power supply were.
BUT - my problem is that one of the leads is TOO SHORT by about 1/2 a cm - going from the CD to the Hard Disk, I can just put the leads but this means one wire (the yellow one, 12V) will be VERY tight. It seems such an irritating and ridiculous problem, to get so far and then not be able to finish it. I suppose I could move the CD down to the empty slot below but this involves more fiddling about and I'm wondering if there's something I'm missing.
The leads go from the power supply to the CD, then to the Hard Disk, then to the Floppy drive.
Any thoughts please????

If you want to spend the money, you can get extensions or splitters for the drive power leads. ($4-$7 US)

Depending where you get them, could be anywhere from 4 to 12 inches in extra length.

Rule #1 Good computers don't go down.
Rule #2 There is no such thing as a good computer.

Hopefully you bought a decent PSU & not a cheapie. How are you drives setup in the case right now & how many are there? Moving one down a bay isn't a big deal....

Asus A7N8X-X
1800+ @ 8.5 x 200MHz
768MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro

also, how many 4-pin connectors do you have running out of your new PSU? Ideally, you should have seperate leads for your CD drive and Hard Drive. If you don't have enough dedicated lines from the PSU, i'd recommend connecting the hard drive directly from the PSU, and then connecting the optical drive from that.

All of the four pin molex plugs are the same. You do not need to hae exactly the same wiring. Just use another plug.

The drives are set up as follows:
CD drive at the top,
Empty drive space
Floppy disk drive
Hard disk drive
With the old PSU there was one cable going from CD to HD to FD.
I'm not at the computer now but will be again tomorrow morning(UK time). I'll look again then at it all and see if I can use separate leads or some other configuration. Presumably I MUST get the colours (ie the voltage?)exactly the same?

Can anyone tell me of a website explaining all this by any chance?

I did get a cheapie PSU - hope it's going to be ok. The reason I'm changing it is that the PC was continuously rebooting before (I'm certain it's not software or virus). If this works I've got 5 more I want to change too.

You will find that all of the plugs that fit will have the same coloured wires (Yellow, Black, Black, Red).

The power supply is only one of the causes of rebooting. As you are in the middle of summer there (It's a chilly winter morning here in Oz), cpu overheating is a common cause of reboots. It may be as simple as cleaning the dust from the cpu heatsinks. (don't use a vacuum cleaner - hugh static problems).

Another cause is poor/oxidised connections. Reseating the Power Supply connectors and the ram might fix these.

Thanks everyone for your suggestions. I used some of the other plugs in the end, and this has worked - thanks Rimfire.

Re the rebooting, I've posted a question here about this before (http://www.computing.net/windowsxp/wwwboard/forum/99573.html) and have had many suggestions from other people. All the machines started doing it not so long after we got them, especially this machine, so I don't think it can be dust, also it looks very undusty in there. loose connections, well the power supply connections have all been reset now.
Before you ask, yes, it goes a through power surge controller, and all the wiring has been checked and redone here.
I'll see if the new power supply makes a difference.
Thanks.

The power supply is very much a possibility in this type of problem. In your other post which you linked above you mentioned that it your computers can reboot during the memory check. This says absolutely that the problem is hardware.

I gather that all of the computers are from the same manufacturer and were bought at the same time. Calling their tech support might shine a light on which component was faulty in that batch.

Another cause of this type of fault is the cpu fan. Either they don't spin up correctly or in the case of recent Acer computers a fault developed in the motherboard which caused power not to be supplied.

Just some food for thought. Let's see how the PSU goes.

Unfortunately changing the PSU didn't help - the PC rebooted about an hour later - dam! I've put the old one back in again so am back to square one.
This time I also took the RAM out and put it back in again, I think that's been done before, but no harm in trying again.

Yes, I too think that it's hardware because of the loop it gets stuck into very often (gets to memory check then reboots, over & over again until I turn the power off).

I did speak to the tech support people who sold us them, and in fact I sent this PC back to them for a few weeks. They ran it for about 3 weeks solidly and say it didn't re-boot once, so they blame it on our electricity supply. That's when we had all the wiring checked and changed here, I think we have built in surge protectors. This computer also plugs into its own surge protector also.

As I said in the other thread all the computers do this intermitently (this one more than most), very often when they're not even being used, but they also QUITE OFTEN will do it when headphones/speakers etc are plugged in or taken out, or sometimes are just touched. (NB they have also rebooted when there's NOTHING plugged in at all - no mouse, no keyboard, no network, not even a monitor!)

People have suggested static, but we have cork flooring, not carpet. Anyway I don't know what the solution is if it's static.

What would I do about the CPU fan?

Someone else suggested updating the Motherboard driver, Rimfire - do you think this would help, and how would I do it?

To start at the end, the motherboard driver tells windows how to talk to the builtin devices on the motherboard without offending them. Your problem is occurring during the boot process even before a boot drive is looked for. Windows drivers are loaded just before you see the desktop.

The simple test for the CPU fan is have a look. If the fan does not spin up properly, the cpu might overheat. Some motherboards will shutdown to avoid damage. Also, with the power off, try turning it by hand. There should only be minor resistance.

Since the boot seems to fail during the memory check, there could be a fault in the ram. Memtest86 is an excellent free testing program. After downloading, run the executable which will create a bootable floppy disk. Let this run for an hour or two. If it does not find any errors, you can be sure there is no problem with the ram.

You mentioned twice now that plugging in headphones can trigger a reboot. Is this a frequent occurrance or something that was observed once or twice only?

1. OK I won't bother updating Motherboard driver.

2. When I put the PSU back I had a quick look at the fan - it didn't look at all dusty and when I blew on it, it spun round, so it's certainly not stuck.

3. I ran Memtest a long time ago and all was well, I think tech support checked it too. Having said that, I'll be upgrading the RAM soon anyway so will take out that RAM and put new in.

4. Re headphones/speakers, this is frequent. Prob 1/4 of the time this is the cause (Sometimes the headphones only have to be moved for it to reboot), 3/4 of the time there seems to be no reason. (As I said before it also reboots if no headphones/speakers are plugged in)

5. I've now brought the computer home to test it here and see if it reboots here .I tried this before but didn't know how to check for reboots, now I know to look at Eventviewer & the eventlog. Will start this evening as I've forgotten to bring the keyboard back. I'm starting to think more & more that it's something to do with the room they're all in.

Very possible poor earthing. But you did say that you have had the wiring redone. An electrician should have noticed this.

Hi Rimfire, I've only just plugged the machine in here so I don't know how it's going to behave yet. But can you explain a little about "poor earthing" please?

One rather odd thing is that we got 7 identical PCs and the 7th PC is in a different room, just next door but separate, and that PC,I'm 99% sure has NEVER HAD THE REBOOTING PROBLEM (all the other 6 PCs have had the problem). I'm fairly sure it's on the same wiring system though and that room was included in all the re-wiring that was done.

Every electrical outlet should have an earth connector as well as the active and neutral. The earth contact should be connected to a large metal spike driven into the ground. The main reason for this is safety, if the active wire should through mishap come into the metal housing of the device, the current would be drawn off to the ground and hopefully a fuse will blow before anybody can be electrocuted.

Another important function of the earth is to keep a constant reference voltage close to zero volts. Without this, the case can collect induced voltages and in turn induce voltages back into the circuit. This can cause havoc in a low voltage logic circuit.

A properly earthed case is also less susceptible to static electricity discharge problems. The lower the resistance between the frame and the earth, the quicker the charge is drained away and the lower the spike voltage.

PC's been running all day (a hot day too) with no problems at all. I've run programs and fiddled with the headphones and just left it running - all fine. Obviously just one day isn't enough but I do feel pretty sure (98%) that it's to do with the room and not the PC. What to do about it is the next question.

Someone wondered whether a large lump of metal might affect it - there's a big kiln in the room next door - could that do anything strange by any chance? It doesn't happen when the kiln is on, but I just wondered whether it just being there affects it in some way.

"A properly earthed case" means what exactly? How can I check the PCs are properly earthed?

I'll check with the electricians that the earthing in the building is ok.

Do you have any other suggestions?

Thanks for your patience & help.

It does seem that the problem is isolated to that one particular room. The majority of causes are in the realm of an electrician. Possibly there is too much load on the circuit which causes the mains voltage to be unreliable and poor earthing has already been mentioned.

Checking that the cases are properly earthed s best left to the electrician also. There are a few simple checks that can be made, but you will need test equipment.

The presence of a kiln in the next room should not have any effect on the computers. While it is operating, it could cause dirty power, but you said the problems occur whilst it is not in use. Perhaps the gremlins use it as their hiding place ;-)

I mentioned static electricity in my last post. This will cause the types of problems you are experiencing. Do you or anybody else find that touching anything metal in the room causes a shock?

I'm of a mind that when the wring was redone, a screw was not tightened or similar. Even electricians have bad days.

PC's been running all day (a hot day too) with no problems at all. I've run programs and fiddled with the headphones and just left it running - all fine. Obviously just one day isn't enough but I do feel pretty sure (98%) that it's to do with the room and not the PC. What to do about it is the next question.

Someone wondered whether a large lump of metal might affect it - there's a big kiln in the room next door - could that do anything strange by any chance? It doesn't happen when the kiln is on, but I just wondered whether it just being there affects it in some way.

"A properly earthed case" means what exactly? How can I check the PCs are properly earthed?

I'll check with the electricians that the earthing in the building is ok.

Do you have any other suggestions?

Thanks for your patience & help.

Should I post the same response as I did when you posted that earlier?

Hi again,

I'm not sure how I managed to post that message twice .... sorry about that.

No, none of us have ever had shocks from anything in the room, I wondered about that too.

Well, I think we'll just have to get the electricians back in to have a look at it all. At least now I have more understanding about it all and know what to tell them.

I think the last thing I'll try before I do that is to move the bad computer into the next door room and see if it fails there, in fact I think I'll try it in all the rooms and I'll then have useful info for the electricians.

This may not be for a few weeks, so all will be quiet for a while. I'll let you know of any resolution. Watch this space!