Memory and Fan funny stuff

[Slacker]

Okay, so I recently decided to double the ram in my PowerBook G4 1.67ghz. I had 1GB and I doubled up to 2. Right after doubling up to 2GB, one of the fans started running at about full blast non stop. I took out the RAM and put back in the old RAM and everything was running okay again. Then I decided to mix and match the RAM and this is what I've discovered:

Situation A:

Slot 1 - 1GB

Slot 2 - 1GB

Result - Fan runs non-stop

Situation B:

Slot 1 - 512MB

Slot 2 - 512MB

Result - Fan runs as normal

Situation C:

Slot 1 - 512MB

Slot 2 - 1GB

Result - Fan runs as normal

Situation D:

Slot 1 - 1GB (same dimm used as in Situation C)

Slot 2 - 512MB (same dimm used as in Situation C)

Result - Fan runs non-stop

I don't understand why the computer behaves differently in Situation C and D. It's the same RAM being used, but only in a different slot. Why can't I put a 1GB stick of RAM in the first slot without having the fans go nuts? By the way, the 1GB sticks are both from Kingston.

Here's something else that I've noticed. I downloaded "Temperature Monitor" and all of the temp values look normal except for "Power Supply Bottomside". Regardless of which of the four situations listed above are chosen, this value fluctuates like mad. I've seen it jump up and down by 20 degrees Celsius in the span of two seconds; it's not uncommon for this value to change by 5-10 degrees in one refresh (refresh rate set to one second intervals). Sometimes it goes up to 76 degrees only to drop again to about 48 after two or three seconds. It doesn't matter if I'm on battery or AC power. I've tried these steps to solve this:

1. reset PRAM

2. reset Open Firmware

3. reset PMU

4. repair permissions

I'm beginning to wonder if I have a bad temperature sensor. Does anyone else have this issue? I'm also wondering if a messed up temperature sensor would be the ultimate cause of the fan going nuts when I have a 1GB stick of RAM in the first slot.

Would anyone have any thought about this?

[Slacker]

Here's some more information...

Situation E:

Slot 1 - 1GB

Slot 2 - Empty

Result - Fans are running non-stop

Situation F:

Slot 1 - Empty

Slot 2 - 1GB

Result - Fans run normal

Apple Hardware test shows no problems.

[CPressland]

now thats what I call strange.

Boot into OS X when the fans are going flat out and run activity monitor, see if it's a process 100%ing causing this.

Also, run smcFanControl so you can see if the CPU is actually running hot, you never know

Hmm, sounds like dodgy ram though, all firmware updated and everything?

Have you tried resetting your PRAM?

[Slacker]

Unfortunately, smcFanControl won't work on a PPC Powerbook. However, I have used both Temperature Monitor and G4FanControl. All of the temperature sensors appear to be normal except for the one called "Power Supply Bottomside". This sensor is reporting a temperature that fluctuates rapidly. It's not uncommon for read temperature to change by 10 or more degrees in on refresh (one second). Is this normal? One one point it will read around 70 or 80 degrees and then jump down to 50 or 60 degrees in one second.

There are no processes using all of the CPU cycles. In fact, this fan problem begins right from when the computer starts up; the fans are running full speed before the grey apple appears. This problem also exists when booted to the OS X install CD.

I don't think that it's bad RAM because the computer is 100% stable and the RAM passes the Apple Hardware extended tests. Also, I have swapped it out for another 1GB stick of RAM (of the same brand and make) and the same thing happens. Whenever any of these two sticks of 1GB ram are in slot one, the fans go full blast. The only thing that I can think is that the RAM is somehow incompatible, but why would this incompatibility only appear when the RAM is in slot one?

The fluctuating temperature thing happens even if the 1GB RAM is in slot two or if it's not present at all. No matter what, the temperature of this one sensor rapidly fluctuates.

I'm using Kingston ValueRAM, does anyone else have any problems in their mac with this RAM?

[CPressland]

Well, i'm using Corsair RAM but I dont see why any other manufacture would have problems running PPC code. after all, ram is ram.

I think your best bet would be a trip to an apple store, the genius bar should look at it for free (they do over here in london)

Sorry i couldnt be more helpful

[Slacker]

Well, tell me if this seems to make sense... That one temperature sensor seems to be acting funny, it's at least no acting like the others. I'm wondering if the whole fan thing is more related to a bad temperature sensor than to some RAM and that perhaps having the sensor fixed might solve the whole thing.

[CPressland]

Yeah the only way you're going to know for sure is going into an apple store :(