Power Supply Power Usage

[dszd0g]

I am starting to put together a new desktop and I am putting the finishing touches on specing it out and looking at power supplies. This is going to be a monster desktop as I am looking at cashing in some stock and putting together a $4.5K system.

The power usage I have calculated is (for brands that do not provide complete power information in their manual/datasheet I used another brand's similar product):

3.3V = 3 + 0.2 + 0.5 = 3.7A 12.21W (34A)
+5V = 2 + 0.5 + 4 + 7.88 + 3.42 + 4 + 1.2 + 0.23 = 23.23A 116.15W (34A)
+12V-1 = 9.2A + 0.3 + 0.6 = 10.1A 121W (18A)
+12V-2 = 6.04 + 7.98 + 1.6 + 0.3 = 15.92A 191W (18A)
Total Watts: 440W

This is with a single DVD-RW in the system. The 7.98A (edit: fixed) on 12V-2 is for 3 15K hard drives. If I add a DVD-ROM drive (1.5A on 12V-2) to the system to be able to do disk-to-disk burns I am up to about 17.5A on +12V-2. This does not sound like a good idea to me.

Is there a good power supply with more power available on the +12V rail? I could always move the hard drives into an external enclosure if I have problems, but I'd rather not as it makes moving the machine more of a pain.

The Antec TruePower II 550W is rated at 19A on both 12V rails. Enermax seems to have more stable rails than Antec in my experience, but do you guys think the Antec would be a safer bet? Going with the Antec would probably allow me to safely add a DVD-ROM to the system.

 

[furballi]

Don't see how you can pull 18A @ 12V with 3 hard drives and one optical. Also note that the devices DO NOT pull 100% load all the same time.

The average A64 system with a 3000 CPU, 1 GB RAM, 1 hard drive, 1 DVD burner, 1 modem, and an average graphic card will consume about 200W at the output stage of the power supply. This is at full load with the CPU at 100% (Prime95) and the DVD burning at 16x.

 

[dszd0g]

CPU: AMD Athlon 64 X2 4400+ 2.2GHz/1MB
110W +12v-1 = 9.2A

Motherboard: Asus nForce4 SLI (939) A8N-SLI Deluxe
3.3 = 3A
+5V = 2A
+12V = 0.3A
(Generic 939 specs, Asus does not provide)

Memory: Crucial DDR PC4000 1GBx2
+5V 4A for two
(Generic PC4000)

Video Card: BFG GeForce 6800 GT OC PCIe
3.3V: 0.1A x2 = 0.2
+5V: 3.94A x2 = 7.88
+12V-2: 3.02A x2 = 6.04

Sound Card: Creative Labs Audigy 4 Pro
3.3V 0.5A
+5V 0.5A

Hard Drive: Seagate Cheetah 15K.4 73GB x3
Startup:
12V-2 7.98
5V 3.42A

Adaptec 2120S SCSI RAID
+5V 4A

CD/DVD: Pioneer DVR-A09XL 16x DVD+RW
+5V 1.2A
+12V-2 1.6A
(Generic DVD-RW)

Vantec Vortex Hard Drive Cooler x3
+12V-2 = 0.1A * 3 = 0.3A

Case: Lian-Li PC70
+12v-1 (fans attached to motherboard) = 0.6A
(Generic case)

Teac FD235HF 1.44 MB 3.5" White Floppy Drive
+5V 1.15W = 0.23A

This is the max power draw, but one needs a power supply that can handle max draw at system startup. Although, another option to look into is some SCSI controllers can start up the hard drives one at a time. That could make a big difference if the 2120S can do that.

 

[Goi]

Dude, a 600W is enough for any conceivable consumer PC system you can think of, especially one from Enermax. Without even looking at your specs, I'm gonna say yes, it's going to be enough.

 

[Sonic587]

Originally posted by: Goi
Dude, a 600W is enough for any conceivable consumer PC system you can think of, especially one from Enermax. Without even looking at your specs, I'm gonna say yes, it's going to be enough.

:thumbsup: