A crater-like dent on G5 processor?

[iamMacPerson]

So a friend gave me a set of 2.7GHz G5 cards to put in my G5, which I did. Once I did, the machine refused to boot and I blamed it on the processor pulling too much power. Well, I tore the machine back apart to reinstall the original 2.0s and noticed there was this crater/dent/chip/hole on the die it's self. Not the card, the die. I was wondering what might cause this and could this have been the reason my G5 wouldn't boot from them?

Thanks!

 

[Intell]

The first problem is the CPU/logicboard mismatch. G5's will rarely, if at all, boot with CPUs other than what their logicboard shipped with. Their fbus is locked to a certain speed that is dependent on the CPU's speed. Without that speed, the board panics and doesn't post or it will put the CPU's in a sub-1Ghz fail safe mode. Any damage to the silicon die will cause the CPU to be unusable.

 

[iamMacPerson]

The first problem is the CPU/logicboard mismatch. G5's will rarely, if at all, boot with CPUs other than what their logicboard shipped with. Their fbus is locked to a certain speed that is dependent on the CPU's speed. Without that speed, the board panics and doesn't post or it will put the CPU's in a sub-1Ghz fail safe mode. Any damage to the silicon die will cause the CPU to be unusable.

That problem with the fbus would explain a lot actually. I put in some 2.3s and it would POST and boot, however it would KP under any sort of load. I guess the 2.7s trying to move the fbus to 1.35GHz screwed it all up to the point where it wouldn't boot. Of course the damage to the die on CPU1 didn't help either.

 

[gavinstubbs09]

The first problem is the CPU/logicboard mismatch. G5's will rarely, if at all, boot with CPUs other than what their logicboard shipped with. Their fbus is locked to a certain speed that is dependent on the CPU's speed. Without that speed, the board panics and doesn't post or it will put the CPU's in a sub-1Ghz fail safe mode. Any damage to the silicon die will cause the CPU to be unusable.

I have to challenge this theory - I have a 2.7 machine that I put a 2.3 set into. The FSB changes to 1.15GHz whereas the 2.7 was 1.35GHz. Even running geekbench, the system scored 2064 and the stock 2.7 scored 2363. Had the processors been in the "locked" 800MHz, wouldn't my geekbench be sub 1400 if they were acting as dual 800MHz? I have yet to have this machine lock up with these processors.

 

[Intell]

I have to challenge this theory - I have a 2.7 machine that I put a 2.3 set into. The FSB changes to 1.15GHz whereas the 2.7 was 1.35GHz. Even running geekbench, the system scored 2064 and the stock 2.7 scored 2363. Had the processors been in the "locked" 800MHz, wouldn't my geekbench be sub 1400 if they were acting as dual 800MHz? I have yet to have this machine lock up with these processors.

Some of the boards will accept other similar CPU speeds, but a jump from 2.0Ghz to 2.7Ghz is too big of a jump. Other boards will refuse to boot with any speed but the speed it shipped with.

 

[sarthak]

Got any pics? It would be interesting to see how a damaged die looks like.

As far as I am aware, G5 machines don't like processor swaps unlike the PM G4. Only if there was a way to flash the machine.

The hard way to upgrade is to replace the board and chip (assuming it fits). It's more economical to pick up a higher spec machine than a new board from eBay.

 

[iamMacPerson]

Got any pics? It would be interesting to see how a damaged die looks like.

Sure here you go!



Regarding buying another machine, I know but I had access to these processors so I figured I would give it a shot. Right now I'm actually on a hunt for a Dual Core model (late 05) and I might actually know where I can get one.