choosing my power supply

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View
Hi all,

I am building a new PC, and I plan to get a ASUSTeK P5W DH Deluxe (Intel
975X Express) - ATX motherborad, with a Intel Core 2 Duo E6600 processor.

I was wondering if the power supply of my actual PC would be enough. It's an
Enermax EG365P-VE 350Watt. it is conforming to the ATX 2.03 standard.
I know there is a special wire for the processor, but I have heard that this
cable used to come from the +5V voltage in the power supply, and moved to
the +12V voltage since processors are asking more and more power. But I
don't know how my power supply is set up, and if it will be working with the
processor I plan to buy. Would you have any hint/advice for this ?

Thank you,


Re: choosing my power supply

AG wrote:
Quoted text here. Click to load it

It has a single rail 12V @ 26A.

Your processor is here. It is only 65W. The Vcore converter will be on the order
of 90% efficient. The current needed would be (65W/12V)*(1/0.90) = 6 amps.

Since you have 26 amps to work with, and the processor uses 6 amps, that leaves
20 amps. You don't say what video card you are using, but even a 120W video card
would only use 10 amps. And then you'd have 10 amps left.

The power supply is not limited by current flow. The overriding consideration
might be the total power the supply can provide. That is 350W. If you had
a 65W processor, a 120W video card, 50W for motherboard and RAM, 30W for storage
devices, that would be 205W total. That is a fair load for a 350W supply, but
should still work.

So I'd say you can do quite a lot with your 350W supply. The combined consumption
of 3.3V and 5V will not be near the 185W limit. Which leaves the total power
as the likely upper limit for the supply.

If you had a mid-range video card, using 60W of power, then that would mean
less heat output from the power supply. And plenty of spare capacity on the
power supply.


Re: choosing my power supply

Quoted text here. Click to load it
Thank you Paul, it is very clear. I managed to find my power supply user's
manual somewhere hidden in my office. I have a different table for DC output

DC O/P Load    |   Max    |    Min
+5V   (Amps)   |   32 A    |    8A
+12V  (Amps)   |   17 A    | 4.25A
+3.3V (Amps)   |   32 A    |    0A
-5V   (Amps)   |    1 A    |    0A
-12V  (Amps)   |    1 A    |    0A
+5VSB (Amps)   |  2.2 A    |    0A

* Max continous total DC output power shall not exceed 350 W
* Max output combined on +5V & +3.3V shall not exceed 185W (as you said)

So it is not 26A but 17A

I changed my mind for an Core 2 duo E6750 and the video card should be a
ASUS EN7600 Silent GS/512Mo, which should meet the requirement of the power
supply. I will also get 2*1Go DDR2 Ram memory.


Re: choosing my power supply

Is this power supply calculator any use?
'eXtreme Outer Vision - eXtreme tools for computer enthusiasts'
( )


Re: choosing my power supply

On Thu, 2 Aug 2007 21:05:40 -0500, davy

Quoted text here. Click to load it

Their calculator is a lot better than some, although some
parts of it are a bit odd such as having to manually specify
for capacitor aging if you wanted the system to be better
able to sustain running hard for a year.  I don't mean we
should ignore this factor, it's somewhat true, though who
/doesn't/ want the PSU to at least last a few years?  Even
if the rest of the parts would be upgraded, PSU might be

However after inputting the figures it then does well to
mention on the next page, "Total Amperage Available on the
+12V Rail(s) is the most important".  IOW, by selecting a
PSU that can handle your 12V needs, it is unusual with a
modern system that you would not have one that also provided
plenty of 5V & 3.3V current.  Often it is more important to
select a brand which you have confidence in being honestly
rated and constructed of quality parts that are not so
effected by penny-pinching that they will be more likely to
keep working long term (capacitors and fans for example).

Site Timeline