[Disgruntled Head of C-3PO]

OK I have had my Dual G5 for a week now and have spend a great deal of time tinkering with it.

As I am sure everyone know that G5's have 9 fans all intelligently controlled bla bla... you know the drill.

Here is the odd part... everyone thinks the G5 chips themselves are the part that need the most cooling, from what I have seen it is actually the hard drives that are cause for concern.

The fan by the G5's is a different type of fan then the one by the processors, it is louder, smaller has a grill covering it and is in the middle of the G5 case right in-front of the hard drives. I also think it has more blades.

If you take the metal panel off the side of the G5 and the plastic cover remains the computer acts the same. The plastic cover however does NOT cover the top bay with the Superdrive and Hard drives. Now the strange part... if you take off the plastic panel I am sure you know the fans kick into high gear, BUT it is not the processor fans, it is the HARD DRIVE fan which isn't even covered by the plastic panel to begin with.

I touched the G5 heat-sinks chips after hours of running and they are room temp, the hard drive however is very HOT.

Other points.

Putting the G5 in Firewire target mode will cause the fans to kick into high gear like no bloody tomorrow, again, it is the hard drive fan that is on the highest and making the most racket, not the processor ones.

Why would the Hard drive fan care if the panel is on or off if it is never covered by it in the first place?

When doing lots of disk use like copying files or permission repairs again it is the hard drive fan that you can hear kick in not the processor ones even though the processors are are maxed out.

Since the hard drive is at the top back of the G5 does it really matter how much heat it puts out as it can easily escape without passing the other electronics?

Does this sound like some sort of bug that the hard drive fans kicks into high gear so easily?

Apple describes the Hard drive fan as "a blower fan" and differentiates it from the other fans in the unit.

Does all this sound normal? Is this the case with older Towers as well?

[Hydra]

Originally posted by Disgruntled Head of C-3PO:


The fan by the G5's is a different type of fan then the one by the processors, it is louder, smaller has a grill covering it and is in the middle of the G5 case right in-front of the hard drives. I also think it has more blades.

Do you mean to say the fan by the HD's is different? I think you're right, the HD's seem to be the hottest running component in my dual G5. I have the original 160GB and added a 250GB drive and they both get hot enough that I can feel heat from them through the rear perforated aluminum back. If I put my hand over the back of the G5 case on and around the two big round exhaust vents the case is cool to the touch if I put my hand over the top back part of the case near the two HD's the case is the hottest. Granted heat rises but the different zones of the case should limit upward migration of the heat somewhat.

-Jerry C.

[Disgruntled Head of C-3PO]

Originally posted by Hydra:
Do you mean to say the fan by the HD's is different?

Yup, have a look at it. It is not a big plastic one without a grill like the others, it is small, loud and apple calls it a "blower fan".

[acadian]

Putting the G5 in Firewire target mode will cause the fans to kick into high gear like no bloody tomorrow, again, it is the hard drive fan that is on the highest and making the most racket, not the processor ones.

Why would the Hard drive fan care if the panel is on or off if it is never covered by it in the first place?

The fans are controlled by OSX. In target disk mode they all kick into high gear by default as the thermal zone sensors are not monitored by any OS.

[wapangy]

There are two fans up there, the one in the back is oriented differently (you can't see the blades) and it sucks air from the back of the motherboard. I think that is the blower, not the HD fan. But yes, this is strange, the HD does get very hot, and i was wondering why apple did not cover it with the plastic cover. Hmmmm....

[Disgruntled Head of C-3PO]

Originally posted by acadian:
The fans are controlled by OSX. In target disk mode they all kick into high gear by default as the thermal zone sensors are not monitored by any OS.

Yes that is understandable, although they do take 5 minutes to get into high gear.

The odd thing is the way the HD fans acts with the plastic cover off when it is never covered to begin with.

[Hydra]

Originally posted by Disgruntled Head of C-3PO:
Yup, have a look at it. It is not a big plastic one without a grill like the others, it is small, loud and apple calls it a "blower fan".

I think that fan is more of a regular fan than the other 4 for the processors but I think the grill is there because it is exposed when you are running with the side door off. The clear plastic shield is always supposed to be in place while the computer is running so the other cpu fans need no grill.

The real blower style fan is the one directly behind the HD fan nearer to the motherboard. It is in a grey plastic shroud and you cannot see the blades at all. I think this is the blower making more noise. This blower cools the complex heat-pipe assembly hidden on the other side of the MB.

-Jerry C.

[Disgruntled Head of C-3PO]

Originally posted by Hydra:
The real blower style fan is the one directly behind the HD fan nearer to the motherboard. It is in a grey plastic shroud and you cannot see the blades at all. I think this is the blower making more noise. This blower cools the complex heat-pipe assembly hidden on the other side of the MB.

-Jerry C.

Hmm, I think you are right about that one. That thing is NOISY when it wants to be.

[Cipher13]

Well, if Apple describes the HD fan as a "blower", then it's entirely different to the other fans in the system; and yeah, unfortunately, blowers are incredibly loud.

However, this is totally understandable; hard drives are the hottest components in modern systems (apart from the processor in some [x86's]), and when you stack two large 7200 rpm hard drives on top of each other... damn.

Next time you're on your old G4, open the case, and feel the heatsinks; cool as. Now feel the hard drives.

[Axo1ot1]

There is also that whole thing about heat rising

[DeathMan]

Originally posted by Axo1ot1:
There is also that whole thing about heat rising

Post some more annoying crap so you'll get banned, but this time do it permanantly.

On Topic:

I've noticed with the portables, it seems to be the HD that gets so hot, too. So maybe we can hope for cooler hard drives in the future. Does solid state storage run cool? Maybe someday they'll be able to get a decent number of bits on something as small as the iPod HD - at a lowish price.

[d.fine]

Holy **** , I got my Rev B DP 2.0 only yesterday, and it is really quite, untill I started to do some HDD intensive work. The fan at the top near the drives kicked in and it makes A LOT of noise ... or it could be the heat-pipe assembly cooler ... according to Temperature Monitor Drive Bay is 32.5°C / 90.5°F.
The CPU fans are spinning very slow, no noise, just as the rest, except for this one fan ... and it is LOUD
The one other component that gets really hot according to TM is the Memory Controller Heatsink, it is at 71°C / 159.6°F ... could that maybe cause that fan to kick in so fast ?

[incubusdaemon]

If you think the 7200 RPM SATA drives are hot, try the 15k SCSI drives. I've burned myself trying to remove one of those before.

Consider: The processors have dedicated fans and large heatsinks. The processor is also relatively flat, for a very large surface area to volume ratio. All of those are good for cooling. (of course, run a processor with no cooling and watch it melt. I accidentally ran an AMD processor with no fan or heatsink. It sparked, melted and smoked within 2 seconds of being powered up.)

The harddisks are in tight quarters with no dedicated passive cooling systems, and are basically a metal brick. I'd guess the HDDs will be hotter.

Also, it's very bad if the top of a heatsink isn't ~room temperature. The very reason it cools is because the top is cooler than the bottom, so you get net heat flow outward on the fins. If your heatsink is hot, your processor is burning. It's also why you blow air on the heatsink instead of exausting air from it. By directly cooling the tips, you increase the heat flow from the processor greatly.

[Link]

As stated earlier, if you ever look at the other side of a g5 motherboard you'll find the system controller and a few other things are linked by a large heatpipe/heatsink combination running around back there.

I suppose that blower fan kicks in whenever a lot of I/O is going on for obvious reasons -- not only are the HDs getting hot but the system controller does a crapload of work.

It makes me wonder why instead of having an elaborate cooling system in the front they stick it back there and make it vent THROUGH the hard drives.

[blakespot]

Originally posted by Link:
As stated earlier, if you ever look at the other side of a g5 motherboard you'll find the system controller and a few other things are linked by a large heatpipe/heatsink combination running around back there.

I suppose that blower fan kicks in whenever a lot of I/O is going on for obvious reasons -- not only are the HDs getting hot but the system controller does a crapload of work.

It makes me wonder why instead of having an elaborate cooling system in the front they stick it back there and make it vent THROUGH the hard drives.

What, exactly, does this large heatpipe configuration attach to in the HD bay to allow it to be cooled? Are there any pics you can find on the web of any part of this? I have a dual 2.5 on the way and would be most curious to see it. Thanks.



blakespot

[Hydra]

Originally posted by blakespot:
What, exactly, does this large heatpipe configuration attach to in the HD bay to allow it to be cooled? Are there any pics you can find on the web of any part of this? I have a dual 2.5 on the way and would be most curious to see it. Thanks.



blakespot

bluebord.jpg

Here you go.

-Jerry C.

[blakespot]

Originally posted by Hydra:
bluebord.jpg

Here you go.

-Jerry C.

Nice find. Where does it break out around the front side and vent into the drive bays? Is there a grille there in the path of the air from the drive bay fan?


bp