10-10-2009, 06:09 AM
You still do not get it, for every 100 W of power going into a computer, about 100 W is going to come out as heat. That is HEAT not the CPU TEMPERATURE, it does not matter whether it is shedding that total amount of heat off a CPU surface at 65 C or at 40 C. But, then you are not the first person to confuse the concepts of temperature and heat. And you better rethink your "RAM doesn't really put out much heat", if you are going to be figuring out cooling requirements for a machine. Typical is around at least 10-12 W when active per 2 GB DIMM of the kind used in the Mac Pro's, less for the type of RAM used in G5's. So 8x2 GB DIMM's compared to 2x1 GB modules would be around 80 W more right there, or as much as an additional CPU. Power dissipation is somewhat higher for 4 GB DIMM's.
As for the drives, as they have gotten bigger, the next generation tends to use the same power as the previous one, so the 160 in the G5 would have been comparable to the power usage of the 320 in the Mac Pro. But, while at it, add about another 10-15 W per active drive, and that is using a "normal" pattern of 40% random seeks, 40% read/writes and 20% idle. Mac Pro can have up to 4 drives and be a supported configuration, while the G5 only 2 drives.
The final big difference is going to be in that PCI Express bus, where the Mac Pro allows up to 300 W usage, and for the higher power video cards supplements that with a direct connection to the power supply. The G5 max'd at 150 W for the video card.
So your contention of:
"A baseline comparison between the two is only logical. If you're going to add on a bunch of hardware to the Mac Pro, you need to do the same for the G5. Comparing a loaded Mac Pro to a basic G5 makes no sense."
One, it does not address my contention that max'd out a Mac Pro can meet or exceed the power requirements and heat output of a G5, and Two, ignores that you can add less to the G5 before the system runs out of space and power.
As for your choice of G5, I picked the late 2005 model because it uses even more power than your example and comes closer to the Mac Pro's max.
They do include a note on that page that just the fans speeding up to handle a higher room ambient temperature will raise the max power by 50 W, or to over 2000 BTU/h.
As for the drives, as they have gotten bigger, the next generation tends to use the same power as the previous one, so the 160 in the G5 would have been comparable to the power usage of the 320 in the Mac Pro. But, while at it, add about another 10-15 W per active drive, and that is using a "normal" pattern of 40% random seeks, 40% read/writes and 20% idle. Mac Pro can have up to 4 drives and be a supported configuration, while the G5 only 2 drives.
The final big difference is going to be in that PCI Express bus, where the Mac Pro allows up to 300 W usage, and for the higher power video cards supplements that with a direct connection to the power supply. The G5 max'd at 150 W for the video card.
So your contention of:
"A baseline comparison between the two is only logical. If you're going to add on a bunch of hardware to the Mac Pro, you need to do the same for the G5. Comparing a loaded Mac Pro to a basic G5 makes no sense."
One, it does not address my contention that max'd out a Mac Pro can meet or exceed the power requirements and heat output of a G5, and Two, ignores that you can add less to the G5 before the system runs out of space and power.
As for your choice of G5, I picked the late 2005 model because it uses even more power than your example and comes closer to the Mac Pro's max.
Quad 2.5 GHz Power Mac G5 (Late 2005)
Two dual-core 2.5GHz PowerPC G5,1.25 GHz frontside bus/processor, 1MB L2 cache/core, 512MB of 533MHz DDR2 SDRAM (PC2-4200), 250GB Serial ATA drive, 16x SuperDrive with double-layer support (DVD+R DL/DVDRW/CD-RW), 3 PCI Express slots, NVIDIA GeForce 6600 LE with 256MB of GDDR SDRAM
Power Consumption: Idle/CPU Max 185 W / 550 W
Thermal Output: Idle/CPU Max 631 BTU/h / 1877 BTU/h
They do include a note on that page that just the fans speeding up to handle a higher room ambient temperature will raise the max power by 50 W, or to over 2000 BTU/h.