Wednesday, July 4, 2012

Power Consumption on Power Macs


In this day and age with most longtime Mac users moving to Intel systems but still having perfectly good PowerPC hardware in the closet, many ask, "What can I do with those old computers? I'm not really a modder and don't need a fish tank. Is there anything close to their original purpose I can use them for?" The answer most people come up with, if it isn't eBay, is some sort of server: a file server, music/media, or even a web server. And given Power Macs have multiple drive bays, they'd seem ideal for this task. There's just the one issue of power consumption. Since these computers will generally always be on, it's a good idea to look at their wattage efficiency to see which models would be best served being servers of the served.

I think everybody knows that G5 Power Macs suck a lot of power. They give off enough heat, so much that they're sometimes referred to as space heaters. In fact, most G5s idle (on but no processor activity) at around 150 watts. As a comparison, most laptops and minis idle at around 20-30 watts and even iMac G5s can idle at less than half the Power Mac's wattage with the screen asleep. So G5s aren't ideal as servers, especially since they're limited to two drive bays.

So let's go back a generation. I assumed the MDD Power Macs would be much more efficient, at least in a processor idle state, since they're equipped with G4s rather that G5s. But this article at Apple's website was a real eye-popper, and not in a good way. The MDDs are practically just as power hungry as G5s. The single processor 1.25 GHz G4 which was the last Mac to boot OS 9 wasn't so bad. It idled at 80 watts, but the others, particularly the dualies, all idled at 130-150 watts. That's asking for a pretty big hit in the wallet when the power bill comes.

You have to go back to the Quicksilvers and Sawtooths to find Power Macs that idle in the 50-75 watt range, and it also so happens that those models are much more reliable than what followed. So if you're looking to utilize a server with multiple drive bays, those might be your best options.

One last note, as a way to conserve power you can run G5 processors as "reduced" in the Energy Saver preferences pane. That might save you a little electricity. Also, G4s can utilize Nap Mode in CHUD Tools. I'm not intimately familiar with this, but googling it will give you plenty of links.

*Dan Knight in comments points out the "big drive" disadvantage pre-Quicksilver Power Macs have with not supporting drives greater than 128 GB without a third party card. Also, in this xlr8yourmac page users report that Nap Mode reduces watt usage in MDDs up to 35% to 40% at idle. Interesting.


  1. i installed the chud tools to enable nap mode, basically what it does is allow for your dualie G4 to run less hot and scale down in temperature when doing nothing or average or less intensive workload vs. without nap mode via chud tools, the dualie G4 will be pushed to the max in temperature even when doing nothing= overheating in the summer and let me tell ya, the nap mode via chud tools will keep your dualie G4 will run more cooler and prolong the life of the macnine. It runs stable with Mac OS X 10.4 Tiger and Mac OS X 10.5 Leopard. It is recommended that dual G4 users use CHUD 3.5.2. I have a MDD Dualie 867Mhz G4 and it has been running great for the past 5 years with CHUD 3.5.2 without issues and no overheating!

  2. Um, pre-Quicksilver you have to deal with the "big drive" issue of no support for ATA drives over 128 GB unless you add a third-party card. Quicksilver and MDD models don't have that problem, which would make Quicksilver or a single-processor MDD good choices here. (BTW, with Leopard and file sharing, you can use a G4 as a remote Time Machine backup drive.) See

    1. Options for the pre-Quicksilver G4 Towers:

      From the above:

      3. Intech SpeedTools


      I've used this for years on my Dual G4 Gigabit Ethernet PowerMac, with a 650GB Seagate IDE drive.

      Works flawlessly.

      I was also incredibly fortunate to find a SeriTek 1S2 SATA controller card - - at GoodWill Computing in Austin Texas for five bucks.

      Again - has worked flawlessly with my 2TB SATA drive for years.

      Bonus - Near the 11th hour, it appears Apple decided that those of us who have had iTools/DotMac/MobileMe for all these years would be SERIOUSLY disgruntled with losing our email addresses because we have perfectly functional - albeit older - hardware

      So, they offered the ability to migrate to MobileMe and still be able to use the old email addresses on Macs that don't meet system requirements for iCloud:

      Huzzah! I didn't need to go buy a new(er) Mac, and I still have my G4 dual processor Gigabit Ethernet PowerMac running OS X 10.5.8 ( ), AND accessing my now-iCloud account, AND with some big storage installed!


  3. Reference on "big drives" - see How Big a Hard Drive Can I Put in My iMac, eMac, Power Mac, PowerBook, or iBook?

  4. I had a dual 1.8 G5, it consumed around 32 Watt while just plugged in and turned off and the same while sleeping. That was my last reason to switch to a macbook. However I liked that monster very much.

  5. Well I would not blame the G5 CPU itself. What consumes in G5 more power and produces more heat than G5 are graphics card and U3 memory controler.

    As I use Linux on my G5 I can monitor direct power consumption on both CPUs and they can go up to 85W when in High performance and fully loaded, but they drop to somewhere around 20W each when in Low performance and idle.

    And that's on my machine - I have 1st generation of G5 CPUs (named 970 v2.2) at 2GHz, made with 130nm technology. 970fx, not even mentioned 970MP on 2GHz draw a lot less power on CPU side.

  6. My long-running fileserver is a Sawtooth G4, but it has a FireWire 800 card, so it's not exactly stock (or using internal bays).

  7. from what i can see, the mac mini is the king of the low idle watt cost. i have a Asus Motherboard running as a nas4free server which serves my files to my macs via AFP frm a RAID array with 4 1TB drives. if i just got a mac mini with a 2TB drive id save on costs because it uses less then 1/3 of the 102 watts (at least according to apples documentation they've posted on the web)

  8. I just took out my 250 GB Western Digital IDE from my single core Quicksilver not too long ago. Always just used it for back up but never had an issue with that Mac seeing it. I know some 2001's QSs had trouble with accessing these drives but I guess it also depends on the motherboard revision, mine being a 2002 model might have been the difference and yes, these really do make good little servers. Maybe not exactly speedy but with only a single Ethernet connection I don't see much difference over the Mac Pro that replaced it but for my electric bill.