Power Calculations & Questions

[oops]

Hi, I have some questions about calculating maximum power consumption.

I'm looking at an ASUS P5LD2 mb and an Intel P4 641 3.2GHz. The processor's maximum power consumption is around 115W. However, the board's consumption is 350W. But does the 350W include the CPU or just the board itself?

In the mb's manual, it says this about the power consumption:

"Use of an ATX 12 V Specification 2.0 -compliant power supply unit (PSU) that provides a minimum power of 350 W is recommended for a fully-configured system. Use of a PSU with a higher power output is recommended when configuring a system with more power consuming devices. The system may become unstable or may not boot up if the power is inadequate."

So do they already include the CPU in the 350W?

My second question is how much power does memory usually consume?

My third question is do I add the amperes together if the PSU I choose has two +12V rails?

Lastly, how do I figure out the amperes used by each component? I'm guessing that if I have the power, I can divide it by 12V to get the amperes?

I hope I'm on the right track. I'm really new at reading whitepapers and stuff so a lot of it is guesswork. I'd really like some help. Thanks!

 

[oops]

Hi, I still don't know the answers to the first and second questions. Are you able to provide further insight?

 

[oops]

Ohhhhhhhh I see. That's clearer now. I was afraid that I might've had to get a $200+ PSU!!!

So if my system has roughly the following...

MB: ~50W, 4.167A
CPU: ~115W, 9.58A
Heatsink Fan: 26.4W, 2.2A
Wireless PCI: 3.25W, 0.65A
Video Card: 24.76W, 3.52A
2xHD: 70W, 5.83A (does this one sound right? It's sorta guessed from the PSU calculator...)
1xCD & 1xDVD drives: 100W, 8.3

Then the max total power I need is 389.41W (~400W) and the amperes required are 34A. So if I factor in some future upgrades, I'll probably need ~450W and 37.5A. Does that sound reasonable or am I really off?

For the memory, is 24A on the +3.3V enough? The PSU calculator says I will use about 80W for 2 sticks. 80W / 3.3V is about 24A. So I guess it would be ok in the worst case scenario?

 

[oops]

Oh ok. Thanks for all the help!

 

[oops]

Hi, I have another question. You said in your PSU101 that we can't calculate the amperes if we're given a net power for several things like +12, +5, +3.3 etc. Is that really true? Because I have an Antec TPII-430. It's specs are as follows:

+5V: 36A
+12V1: 17A
+12V2: 17A
+3.3V: 28A
-12V: 1.0A
+5Vsb: 2.0A

It says that the +5V, +12V1, +12V2, and +3.3V maximum load is 410W. So does that mean I might not have enough amperes for all the devices in my system? :?

 

[ZOldDude]

You really don't go by "wattage" these days as much as amps the the 12 volt side...and try to use a PSU that has all the 12 volt pwr on ONE rail and non-modular to avoid all sorts of problems (load balance/connection loss etc).