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eegg0923754
Mar 28, 2012, 02:06 AM
Hi,
I have 2 dual 1.25 MDDS and overclocked both to 1.5GHz. I was running one machine just fine, wasnt running the other as I hadnt gotten RAM for it yet. So I decided to switch out the 2GB RAM from one machine to other in order to test the 2nd machine that I had yet to use. It booted up very slowly in about a minute compared to 30 seconds with the 1st MDD I was using. Then OSX froze and I restarted twice. Again slow boot times and freezing. Finally got Safari open and went to a youtube video only to recieve a kernel panic. Now when i try to boot I get the bong/chime but then no video.... Some suggestions would be helpful. What could be causing this kernel panic?

P.S
I havent added new thermal compund to either CPU since I overclocked them (I will in the future, right now I'm just testing the machines) but I really have a hard time believing that the CPU would kernel panic without even being warm or running heavy programs.



WAM2
Mar 28, 2012, 02:18 AM
Hi,
I have 2 dual 1.25 MDDS and overclocked both to 1.5GHz. I was running one machine just fine, wasnt running the other as I hadnt gotten RAM for it yet. So I decided to switch out the 2GB RAM from one machine to other in order to test the 2nd machine that I had yet to use. It booted up very slowly in about a minute compared to 30 seconds with the 1st MDD I was using. Then OSX froze and I restarted twice. Again slow boot times and freezing. Finally got Safari open and went to a youtube video only to recieve a kernel panic. Now when i try to boot I get the bong/chime but then no video.... Some suggestions would be helpful. What could be causing this kernel panic?

P.S
I havent added new thermal compund to either CPU since I overclocked them (I will in the future, right now I'm just testing the machines) but I really have a hard time believing that the CPU would kernel panic without even being warm or running heavy programs.

Sounds like a memory issue, reset the PRAM, if that doesnt help, reseat the memory.

eegg0923754
Mar 28, 2012, 02:11 PM
Sounds like a memory issue, reset the PRAM, if that doesnt help, reseat the memory.

I tried both of these, doesn't seem to be a memory issue as this same memory worked in other mdd just fine. Today again I tried to boot and got a kernel panic and then no video whatsoeve on any boot attempt after that. I swapped out the video card, but still no video. It's not the hard drive because I've tested it in another machine. I doubt its the PSU either because the machine powers up and chimes and I can hear the fans and hard drives powerup. I'm starting to think more and more that it is the CPU and it lacking thermal paste, because it only boots once and that's it...:confused:

eegg0923754
Mar 28, 2012, 04:12 PM
Update: It was in fact the cpu, I swapped cpus on my mdds and now it works. I guess I will be needing the thermal compund to simply boot the machine or maybe the cpu is bad. It was really weird though, how I couldn't even get video off of it.

ThunderSnake
Mar 28, 2012, 06:00 PM
Fresh thermal compound is a must. You should not even be testing them without it. Read here for more info:

http://www.jcsenterprises.com/Japamacs_Page/Blog/9AE7FE0E-0CF2-4A7C-8003-489B282582BC.html

When you do this, look to see what is marked on the die. 7455B is a good candidate for overclocking. 7455A is not. 7455A is best left alone.

666sheep
Mar 29, 2012, 01:25 PM
OP, never test OC'ed CPUs without fresh/good thermal paste, otherwise you may see how burnt G4 looks like ;)

Bump voltage on this "bad" CPU (one step up) and it should work OK.

eegg0923754
Mar 30, 2012, 01:29 PM
OP, never test OC'ed CPUs without fresh/good thermal paste, otherwise you may see how burnt G4 looks like ;)

Bump voltage on this "bad" CPU (one step up) and it should work OK.

Thanks for the input, I've also gone ahead and purchased some copper heatsinks (for $30!!) that came witht he DP 1.42 for these MDDS, thye should be running much cooler now :D

666sheep
Mar 31, 2012, 03:19 PM
You may want to install Chud Tools and enable Nap mode. It will lower CPU temps by few degs, especially when idle.

eegg0923754
Apr 6, 2012, 11:00 PM
OP, never test OC'ed CPUs without fresh/good thermal paste, otherwise you may see how burnt G4 looks like ;)

Bump voltage on this "bad" CPU (one step up) and it should work OK.

hey 666 sheep, I did as you said by bumping up the voltage, it worked for like 5 mins then it kernel panicked again. Should I bump it up one more step or is it pretty much useless now?

666sheep
Apr 8, 2012, 02:59 PM
Check your solder joints, maybe one is bad -> fix it if so.
One step up won't hurt too, however first try above and test.

eegg0923754
Apr 11, 2012, 09:26 PM
Check your solder joints, maybe one is bad -> fix it if so.
One step up won't hurt too, however first try above and test.

I'm pretty sure the soldering was ok and if not it would have been the 2nd bump up in voltage from the original settings. I removed the soldering in order to make sure it was the second bump up, but the mac wont boot, I usually get a folder in the middle of the screen with the question mark and then a few seconds later finds my HDD or installation DVD. But this time all I got was a very little piece of the top of that folder and then it stopped, so I figured another kernel panic... I will try to better solder the joint again, but is it possible the CPU really is unrecoverable at this point? :( The daughter card itself looks fine, as do the processors..

eegg0923754
Apr 14, 2012, 04:41 PM
Check your solder joints, maybe one is bad -> fix it if so.
One step up won't hurt too, however first try above and test.

I swapped CPUs with another one I had and it worked but I still want a dedicated CPU for this machine, I've given up on this "bad cpu"

What CPU is better for overclocking the DP1.25 or DP 1.42?

666sheep
Apr 15, 2012, 01:30 PM
Try other freqs on this "bad" CPU (1.42 GHz or lower).