Mac desktops forum: my i mac g5 20&quot; will only boot with 512 memory installed

new caps

by nannook22 - 2/14/12 1:32 PM

In Reply to: This problem might be something else by mrmacfixit

well i just replaced all the caps guess mob is bad

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You replaced them yourself?

by mrmacfixit - 2/14/12 5:08 PM

In Reply to: new caps by nannook22

Taking that as a yes, did this RAM problem exist before you changed them out or did you not try to increase the amount of RAM before that?

It is very easy to damage a logic board when driving a soldering iron around.

P

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bought it used

by nannook22 - 2/15/12 3:07 AM

In Reply to: You replaced them yourself? by mrmacfixit

not sure bought it used with bad caps would not power on at all i can see if one slot was bad but the 512 stick will work in either slot just never seen that before

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Answer Best answer as chosen by user nannook22

One other thing to consider

by Jimmy Greystone - 2/15/12 5:23 AM

In Reply to: my i mac g5 20" will only boot with 512 memory installed by nannook22

One other thing to consider is that it's entirely possible that the MLB simply cannot handle 1GB density RAM. The G5s are pretty old, and 1GB RAM modules quite possibly didn't exist when the unit was being designed, or were so expensive at the time that the system designers did not bother factoring them in. It's something often overlooked by people, that to a computer there's a big difference between 2x512MB and 1x1GB. A lot of people may just see that the maximum supported RAM is 1GB, and so think that they can get to 1GB any which way they please, but it just doesn't work that way in the real world.

2x512MB might be the maximum supported configuration for that unit. If the 1x512MB config works regardless of memory bank, then odds are the MLB is fine, and the problem is you are trying to use a RAM density that the unit can't handle. If you have another 512MB module, you could try putting the both of them in to see if it will POST and boot, and I'm betting it will.

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yes i have 2 512s

by nannook22 - 2/15/12 2:43 PM

In Reply to: One other thing to consider by Jimmy Greystone

i tried that only work with one of the 512s either one either slot but not both wierd huh i have another i mac g5 20" with same dual 2mhz and i run 2 gig ram in it works fine the 2 are the same model i was thinking could the power supply be weak ahh it prob;ey just the board

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That would be something

by Jimmy Greystone - 2/15/12 4:35 PM

In Reply to: yes i have 2 512s by nannook22

That would be something for the PSU to be so weak that an extra couple bits of RAM would take it down. Considering the RAM probably only uses 1-2W of power, if that.

But I'd say if you managed to get the thing working at all from a non-working state, you came out ahead, so just be happy with that.

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