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How do you fix a computer? Answered

Hi everybody,

I am hoping you can help me fix my power mac G5 dual processor computer I brought from ebay.

My dad and I managed to start it up for the first time, it had no operating system, (because we had put in a new hard drive) so we installed the panther operating system onto the computer and we shut it down. But when we tried to start it up again, it won't start up.

The little white light next to the power button flashes three times, and according to the manual, there is something wrong with the RAM. We them replaced the RAMs with new 1GB ones, but the computer is still not working.

We think there is something wrong with the motherboard (logic board). But we don't what is causing the problem...

Any of your suggestions would be greatly appreciated!

- Plasmana


And put Windows 2003, Xp or vista on it and try that

Ooh thought tear it apart and write down what part goes where and get the motherboard make and model and go to newegg.com and see if they have it

I would say UPS it to me but im not familiar with dual processors and a setup like that. Im used to the older computers


Actually there are a few that use specific code to make the reader-arm in the harddrive scratch the discs thus inflicting physical damage to the drive atleast.

Maybe its a virus...

No, I fond there is something wrong with the motherboard... Besides, there are no viruses created to infect mac computers. (I think)

there are viruses to infect macs but they arent all that common, because well macs arent as popular and therefore get less viruses total giving apple more time to spend on each virus(to get rid of it). In 2007 there was around 1,000 viruses for make and 114,000 (known) viruses for microsoft.

Damn! Those poor microsoft computers are really suffering more than I thought!

yeah,the ram cover on my laptop is the hot spot during use so it suffers from windows i thought it would be the first part to go on the laptop any way i can but laptop sdram on turkey for cheap

Linux? Do they have very few or no viruses?

i am not familiar with mac but am with linux (i use it). i think the main causes for lack of viruses in linux (and probably same for mac) are the users - most linux users have better common knowledge in computera. they are less likely to do something stupid the system - its harder for an unwanted evecutable to get run on the system without the user wanting it. (not as easy as autorun on usb disk or coolshot.png.exe)

I hear macs are picky about RAM, but I'm a PC guy so I wouldn't really know. You could try just reinstalling the RAM, but if that doesn't work I'd guess you're right about the mobo.

see if you can find the motherboard on ebay, it would be much simpler to just swap it out rather than tying to fix it. also, is that mac watercooled?

I am planning to buy an motherboard from ebay, but I want to see if I can fix the computer... No, it is fan cooled.

One thing to consider; in certian computers if all the ram bays arent filled there is a certian bay that has to have ram in it. For example in my laptop there are two ram bays, currently I have two 1/2 GB sticks in there to make 1 GB or ram, but if I wanted to put one 1GB stick in instaid of two 1/2GB sticks I have to make sure the ram is in the first bay or the computer wont recignize that there is any ram at all. The bay it has to be in varies depending on the motherboard, try loking in the manual under ram or motherboard (if you have the manual that is)

my thinkpad had ram on slot 2 when i bought it,maybe it is the required slot

I suggest you try resetting the PRAM.
Read this one here

If that doesn't work. You can try a hardware test to figure it out.

If those yeild no results, try booting up into the install disk again, and choose disk utility from the menu erase the HDD as mac os journelled, then try reinstalling.

At that point, if you still have had no luck, either ask me for more advice, or contact apple.

None of your suggestions work... :-(

My dad has one question for you, he wants to know what is a PMU and how to reset it.

I can give you more problems the computer is showing.
  • The computer has no video output.
  • The superdrive won't respond - we even tried to force it open by pushing a special button or something.
  • The fans start out normally, but they then slowly go up to full speed, it sounded like there is a tornado going on in the house.
  • The computer won't respond to the keyboard commands.

There are more, but I can't think of any right now...

Okay, I have done some research and found this. It appears a lot of people's G5 computers are suffering the same problem as mine, and none of them said the cure for the problem...

Ok, looking more serious then, it could be many problems, that thread seems to think that booting into firmware might help. Read down the thread, and you can see some suggestions about that. Otherwise, it looks like a trip to the macshop.

I have found something interesting, the PRAM's backup battery is 'dead'. I tested it with a 100mA load and the voltage drops dramatically - from 3.6V to 0.8V. Do you think that could be the cause of the problem? If its not that, then my last hope would be something to do with the RAM's... I read that G5 computers are very picky about what RAM's you give them.

That could be it! good thinking, a new battery might just solve the problem.. once the new battery is in, reset the PRAM.

Okay, my dad replaced the battery, and the computer still does not work... :-(

time to retry disasemble to pieces and assemble again or maybe the fire hose method. it works for most pentium 2 - 3 s and sometimes newer pcs too

sounds like the logic board...

Thanks for telling me that, my Dad just ordered a new battery. The battery is really weird looking too, it is a 3.6 volt lithium ion battery with a size of an 1/2 AA...

I could, but I don't want to risk damaging the computer more by giving it incorrect voltage.

it's supposed not to get damaged by a weak battery (that gives 3 V instead of 3.6)

They're great Macs aren't they? Out of the box, plug 'em in and you're off. Try fiddling with 'em and it's a different matter. You've said that you had no operating system, "because you put in a new hard drive", which implies that you have the old one - do you? L


9 years ago

So it stayed up long enough for you to do a full panther install with the original memory? I would think that would indicate a certain amount of "goodness" to the machine as a whole. You may want to restore it to the original set of components that were in there when that install worked. You didn't like DROP it or something in between the install and the "not working" state? :-)

It certainly sounds like one of the PMU issues; they can cause a mac to look pretty dead, though I don't recall seeing your exact symptoms. See here; the PMU reset button is relatively obvious.

My general "how to fix a computer" rules:
1) clean anything that's dirty.
2) re-seat any socketed components and/or cables that may have been dislodged.
3) Start with as little hardware as possible, preferably "known to work" components (ie remove HD and boot from CD, use minimal RAM, etc.) (You might remove one CPU or the other; I don't know how hard that is in a G5.)

*Try to reset the 3V battery on the mother board. *Try to test each component individually, especially the mother board. *Test the power suply whit a multimeter, to see if it is working properly. *Check the connection on all the cables, again whit a multimeter... *Maybe you just need a graphic driver that came whit your monitor, my mac showed a black screen until i didn't put the CD that contains the driver for my monitor. Sorry, no more ides, hope you get if fixed... :(

Sorry Plas, But I'm not good with macs :-( I wish I could help.


9 years ago

Where did the computer ship from? Some places have such bad shipping that they completely damage the northbridge. Can you locate the CMOS reset jumper? It should be a small button or lever-like thingy. If your computer came pre-overclocked just be aware that by pressing that your CPU's clock speed returns to normal, that is, if your CPU still works. Maybe your old RAM was broken and you replaced it with the wrong RAM? G5 computers are picky about RAM. If nothing works, just buy a new computer, and make sure it's windows. Out of all these computers I've used, PCs have been more reliable than anything else.


9 years ago

Test the hard drive and RAM in another computer if possible...

Both the RAM and the hard drive are new...

Still, don't rule it out completely. I have gotten new parts that were defective already, in fact I had it happen to me with the same part, twice in a row, before they got me a working one. It may be rare, but it can happen.

I later found out that the G5 computers are very picky about what RAM you give them, that could be the problem... But I still don't understand why the superdrive, hard drive, and video card does not work? And the fans slowly speed up to full power after 30 seconds...?