Powersupply calculation....

ex_forum_user_3

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GENERAL OF THE ARMY
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Jul 3, 2002
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Hi there,

To give a better guide on powersupplies.....

Modern AMD CPU's (XP) need about 180W on the combined 3.3+5V power lines....
Check the label on this.....
If it doesn't list the combined wattage, you can try this (refined) calculation:

((5VxAMP's+3.3VxAMP's)/3)x2=approx the wattage for most powersupplies.....

Eg.

You have a PSU that does:

5V 20A
3.3V 15A

It will do about:

5x20=100
3.3x15=49.5
100+49.5=149.5
149.5/3=49.9
49.9x2=99.8Watt's combined

Be aware, this is only an example.....
It can give only an estimate on most PSU's....Cheap ones, there are far better......and this is the calculation for the worst type's :p

You better check the label for the exact combined power...

The best rule to stick by is 180W combined for a XP-1700 under normal conditions.....
200W or above for the same system with a GF4Tixxxx or simular card....
 

Scirocco

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SERGEANT
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Jul 6, 2002
Messages
45
thanks for the general formula Bas.
Have your morning coffee or beer in the afternoon?
:D :]
 

r@id

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Jul 23, 2002
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I have no broblem running my computer with a "small but damn enough" power supply...

I also have 3 case fan running @ 7v and 3 other small fans (chipset+video+cpu)

2 cd roms and 2 HD...

I'm running a computer not a powerplant...! :)

 

ex_forum_user_3

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23,397
Hi,

Harddisk's, Cdroms, CDwriters and fan's are not the stuff that take much power.....
They take most from the 12V line....and that one has plenty power on most PSU's.....

The really powerhungry stuff on 3.3+5V are:

CPU (XP-1800 about 80W at full load!)
Motherboard (depends on the board and features)
Ram (estimated at 10W per 256MB no matter the load)
Videocard (GF4Ti a lot, but close to the CPU! when full load)

So you see, 180W combined isn't really that much....
And you know why underpowered systems crash when playing games......
As at idle, they don't take that much......

12V even when you have only 10A is allready 120W....
Get the picture there???? :]

 
L

lnpuco

Guest
I am running an AOpen 300wps, Large Mid-Tower, with an MSI KT333 ARU, 1800+, 768 DDR Micron, MSI G4 MX440, Dual Maxtor ATA-133 7200 rpm drives, Acer 56x CDR, LiteOn 16X48 DVD, LiteOn 40x12x48 CDRW, 1.44FDD, Iomega 100 ide zip, AOpen 56k Modem, AOpen 10/100 NIC, etc, etc, and WinXP Pro as far as the op. and no power supply problems, and that includes 5 8x8 case fans....just some notes for the crowd...later
 
M

Mankou

Guest
I ordered a 1800XP and a GeForce4 Ti4200 for my K7T Turbo. There are also 2 IDE drives, 2 HDs, 2 PCI cards, an extra case fan. My PSU is an old generic 230W. GOD HELP ME! 8o
 

ex_forum_user_3

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Hi Mankou,

You better get a bigger PSU.......it won't handle it at all :]
If it will even start (doubt it very much), you will run into trouble when you put some serious load on it....
 

ex_forum_user_3

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Hi,

I have seen that link before, although not accurate anymore it a good guide on the wattages.....
 
S

Snead

Guest
I've been having trouble running a Mushkin 512M PC2700 module. My computer runs fine with the 256M PC2700. It has been suggested I replace the Antec 300W PS with a larger one. Mushkin support thought 300W should be enough but I have ordered a 500W PS replacement just to be sure I have enough power. What do you think?
KT3 Ultra ARU
AMD 1900XP+
Two Maxtor ATA133 80 Gig 7200 in RAID 1 config.
CDR,CDRW and DVD
Gigabyte ATI 7500 AGP
IEEE1394
MSI USB bracket, S-Bracket and D-Bracket.
SB Live audio
Tech Floppy
USB mouse
Logitech Wingman Force
External USR Courier modem
USB printer and parallel printer.
Two small Aux fans
 
E

emh125

Guest
I am in the process of putting together a computer for the first time and the motherboard that I like is the KT3Ultra. My question is, in looking for a case, I don't know if the connectors from the power supply are universal between AMD motherboards and Intel motherboards. Can anyone tell me what to look for? The case I was looking at is the Antec SX630. Thanks in advance for your help :]
 

Wonkanoby

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tweety if you use the formula

and if ive done my sums right that psu still only gives 166 watts cmbined

 
Y

yoyiyo

Guest
darn,i only got 164watts out of my so called 400watts p4 power supply,and i'm running XP@1630 wif vcore 1.7v ,sdram based mobo wif gf2,dvd,7200rpm drives and audigy..is that enuf?????
 

Wonkanoby

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Messages
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the calculation is only a guide

the sums do not work on an antec true power as it has totally independant 5v and 3.3 v rails but its the only one i have found to date to be like that

the best thing to look at is the quoted combined figure

if they dont quote it appears to me they are normally of inferior quality and a good guide in the main to avoiding them in the first place

if your pc works with what you have fine

but if you get odd lock ups and other strange behavior
then you have an idea as to what may be causing it
 
Y

yoyiyo

Guest
hehe...mmm..guess i don hav any probs now...my sys is stable :) even my 5v reads 4.83v somtimes
 
T

tweetyoost

Guest
tomorrow i have something better a 550w psu :p
that should to i think :D
 
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