How many Hard Drives ?

Question

I've been fortunate to receive a PowerMac G4 733mhz (Digital Audio) along with a Sony 20" CRT monitor at no cost and I'm looking to get all the performance that I can out of it.
So far I've maxed out the RAM and added an iogear USB 2.0 card along with a SIIG Utra ATA 133/100 Pro controller card. The Radeon 9800 pro video card is a couple weeks away yet.
I now have a 160gb and a 60gb as master/slave on the main board, and another 160gb on the controller card in which I'm adding another 80gb to tonight.
I am wondering how many hard drives I can add before I have to start worrying about the power supply. Keep in mind that I'm going to be adding the video card in the future.
I also see that SIIG card says OSX 10.1 or later, does this mean that I cannot connect a drive that boots into OS 9 to the card? Or a drive that may have Yellow Dog Linux?
Thanks, I'd appreciate any input about this new project of mine.

Answer 1

Hi-
OK, let's talk power.... This is what we have to work with (may be slightly higher depending on PSU model):
DA 338W PSU
+5V=20A
+3.3V=24A
+28V=4.04A
+12V=8A
-12V=0.25A
Total on combined +3.3V and +5V =126W @32A
Of course, there is a big difference between idle and load power consumption, but I will list maximum power consumption values. Various requirements are:
ATA/100 Hard drive- Read/Write, approx. 12.8W [email protected], [email protected]
Optical Drive- Full Speed (42x) read, approx. 5.6W [email protected], 15.7W [email protected]
Memory (per 512mb DIMM) 1-3W combined 3.3V,+5V,[email protected]
PCI and AGP slots combined max +3.3V, +5V=62W, AGP (only) up to 20W
Firewire Bus 15W+25V
USB Bus 5v@500mA per port
733mhz PPC processor 1.6V 15.6W (Idle) 22.0W (load)
Fans (combined) +12V [email protected]
As for the Radeon 9800 Pro, under full load, the power requirements are:
+5V [email protected]
+12V [email protected]
+3.3V(AGP) [email protected]
+5V (AGP) [email protected]
+12V (AGP) [email protected]
Points to consider (no particular order):
-An ATA hard drive at idle, will still pull 7.2W and at Standby, will pull 1.4W.
-Unless you are running 2 RAID sets, you would rarely, if ever, have 4 drives simultaneously in Read/Write.
-One process that will push a system to the max is disc burning. Consider CPU at load, one, possibly two hard drives at Read/Write load, and the Optical drive at load. (For all who care, this is why we don't multi-task during burning). Without multi-tasking, the graphics power draw is minimal.
-Weak point of early ATX PSU revisions was the 12V rail. The G4 PSU also has a weak +12V rail (only 8A).
(Run a dual internal RAID, and try to burn a disc..... well, you better set the machine up as a headless server.....)
-Total combined +3.3V, +5V wattage and ampherage is sufficient for most fully loaded system and bus combinations.
-The power requirements of the 9800 Pro are all within the maximum limits of the various voltage rails of the OEM PSU.
-A 237W PSU equipped Sawtooth will run without problems with two hard drives (one system, one storage), a 2.0ghz 7447 processor, USB 2.0 PCI, Radeon 9800 Pro and AC VGA fan. Additional hard drive (scratch drive), PCI cards, HDD fans and lighting overload the +12v rail for operation at load with disc burning. (we're talking about real life experience here...)
-Hard drives are heat producers, and an external firewire connected housing can allow for better overall system operation by reducing interior clutter and heat production.
-High interior temperatures reduce the ability of the PSU to cool itself, and thereby reduce it's ability to produce reliable power under load, in the heat.
-Old ATA hard drives are power hogs and hot in comparison to current SATA drives. Switching to two larger SATA drives will reduce load requirements by 3-4W per drive, as well as reduce heat production. Required use off a SATA PCI controller card eliminates the capacity restriction of the native ATA controller. Switching to SATA saves space, power, and cooling needs.
-And, final (random) thought to consider, a dual 500mhz Gigabit Ethernet (same PSU as the DA) will run two ATA drives simultaneously, burn a DVD, with a 9800 Pro installed, without any problems whatsoever. The same machine will run 3D graphics intensive games at enjoyable framerates, without problem. Internet video, on line games, etc., are all enjoyable, with reasonable performance for the given CPU speed. All uses of the machine are without problem, with the added graphics benefit provided by the 9800 Pro (Yep, another real life experience).
Now, you decide....