12V current with minimum of 20A for 7900GS

[shadowjagans]

well ok, my friend's 6600 fried the other day and he wants to get a new card now, hes planning to get a 7900GS and according to leadtek:

http://www.leadtek.com/3d_graphic/winfast_px7900gs_tdh_2.html
*A minimum recommended 350W system power supply (with 12V current rating of 20A).*

well i hardly know anything mch about PSUs but i doubt my friend's 2 year old comp has a psu with a 12V current rating of 20A.

unfortunately i live in australia, so most of the online stores such as newegg wont b a good suggestion

the cheapest store in my area would b MSY and heres its price list:
http://msy.com.au/Parts/PARTS.pdf
the PSUs r listed on the second page near the mid-lower right

can anyone tell me which one would hav a 12V current rating of 20A?
(don't bother with the SHAW brand, i herd they really suck)

Thanks in advance =]

 

[shadowjagans]

ok i just asked around and i noticed one of my friends has a 7800GTX and according to leadtek:

http://www.leadtek.com/3d_graphic/winfast_px7800gtx_tdhvivo_2.html
*A minimum 350W system power supply with 12V current rating of 22A required (When running in SLI configurations, 500W system power supply required.)*

But the PSU he has is a Coolermaster Real Power 550W SLI and according to coolermaster:

http://www.coolermaster.com/index.php?LT=english&Language_s=2&url_place=product&p_serial=RS-550-ACLY.&other_title=+RS-550-ACLY.+Real%20Power%20550W%20SLI
one of its 12V only has a peak of 20A

how does that work out? im confused.....

 

[doolittle]

The RS-550 spec shows 360w total +12v so that gives you 30A - It's a decent unit.

The 7800 gtx maxes out at 81w (6.8A) stock and 108w (9A) overclocked.

The 7900gs is a miser at only 45w (3.8A).

 

[shadowjagans]

so its the total of the 12Vs (12A+12A+6A=30A) that count and not just one of them?

 

[shadowjagans]

but then if the 7900GS only uses 3.8A, y does leadtek suggest 20A?

 

[doolittle]

Yes that is what the manufacturers are recommending, the total +12.

Also looking at the list, I would probably pick any of these brands

Antec true power 2 (any, but not smart power)
antec NeoHE (any)
cooler master RS-450 / RS-550 / iGreen (any)
Topower (any)
OCZ (any) budget permitting

 

[jaguarskx]

but then if the 7900GS only uses 3.8A, y does leadtek suggest 20A?

Because the power supply has to power the entire PC not just the GPU. If you can figure out how to run the rest of the PC without being plugged into an outlet then please let me know.

Also manufactures do not know what components you are using. For example, the Core 2 Duo E6300 CPU only uses 44w under 100% load. But the Pentium D 805 consumes 145w of power under 100% load. That's over 100w more.

 

[shadowjagans]

well this is roughly what he has:

AMD Athlon 64 3200+
Foxconn NF4K8MC-RS
1GB DDR400 (duno what brand)
and things such as:
DVD Burner
DVD ROM
Floppy

i haven't checked his PSU yet but i think its 550W
the 7900GS requires a 6pin pci-e power connecter rite?
not sure if he has one of those...

but lets assume he does hav a 6pin pci-e power connecter
and it has a +12V of 18A, would it b able to support the 7900GS?

 

[jaguarskx]

i haven't checked his PSU yet but i think its 550W
the 7900GS requires a 6pin pci-e power connecter rite?
not sure if he has one of those...

but lets assume he does hav a 6pin pci-e power connecter
and it has a +12V of 18A, would it b able to support the 7900GS?

Yes, the 7900GS requires a 6 pin power connector.

A bare minimum of 18A is suggested. I based on your friends specs and assuming he is only using one hard drive, I estimate he will be using about 16A on the 12v rail under a full load. Most 550w PSU provides at least 26 amps on the 12v rails so your friend should be ok.

It's best to open up the case and look at the PSU sticker which should tell you the available amps.

It is important to note that any overclocking will also draw more power, thus increasing the minimum required amps.

 

[shadowjagans]

well we went to go and buy it today and its workin great, jus hope it doesnt fail on him bcoz theres not enough power...

but anyways thanks alot everyone =]