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Choosing Power Supply

E

EscaroN

n00b
Joined
Jul 30, 2004
Messages
57
I'm just building my new system right now and I'm buying the Saphire Radeon X1900XTX, it says on newegg it requires a minimum 450Watt power supply with 30A on the 12V rail, now I've been looking at a lot off different power supplies and most of them have more than one 12V rail, sometimes 2, each of them having about 18A on average, now does that mean that during operation the 12V rails can combine their amperage to give me my 36A or will I not be able to run the graphics card without that. The reason I also ask is that if in the future I want to upgrade to Crossfire it says "For CrossFire: 550 watt power supply or greater, 38 Amps on 12 volt rail ", the power supply I'm considering buying is:

OCZ 600W GameXStream Power Supply w/ Quad +12V
+12V1: 18A
+12V2: 18A
+12V3: 18A
+12V4: 18A

Does this mean if I start running a Crossfire set up it can potentially run 72A on the 12V rail and that I would be able to run the cards perfectly stable?


If it matters, I'm going to have either the E6700 or E6600 running with that, a PCI sound card and only one HDD :p
 
When looking at supplies with multiple 12V rails, you want to look at the combined rating, in watts or amps. If you run crossfire with that card then you will need something really powerful.

Crossfire: 600W or more from Fortron or Seasonic.
No crossfire: 500W from Enermax.

Just what I would do.
 
dBTelos said:
When looking at supplies with multiple 12V rails, you want to look at the combined rating, in watts or amps. If you run crossfire with that card then you will need something really powerful.

Crossfire: 600W or more from Fortron or Seasonic.
No crossfire: 500W from Enermax.

Just what I would do.
Click to expand...
The OCZ he's looking at is a Fortron ;)
 
The OCZ 520 Watt will be plenty for what you need. I run alot more on one of the 520's, see sig.
 
EscaroN said:
I'm just building my new system right now and I'm buying the Saphire Radeon X1900XTX, it says on newegg it requires a minimum 450Watt power supply with 30A on the 12V rail, now I've been looking at a lot off different power supplies and most of them have more than one 12V rail, sometimes 2, each of them having about 18A on average, now does that mean that during operation the 12V rails can combine their amperage to give me my 36A or will I not be able to run the graphics card without that. The reason I also ask is that if in the future I want to upgrade to Crossfire it says "For CrossFire: 550 watt power supply or greater, 38 Amps on 12 volt rail ", the power supply I'm considering buying is:

OCZ 600W GameXStream Power Supply w/ Quad +12V
+12V1: 18A
+12V2: 18A
+12V3: 18A
+12V4: 18A

Does this mean if I start running a Crossfire set up it can potentially run 72A on the 12V rail and that I would be able to run the cards perfectly stable?


If it matters, I'm going to have either the E6700 or E6600 running with that, a PCI sound card and only one HDD :p
Click to expand...

12v combined amperage is determined by the rectifier that feeds the 12v rails. If it is capped at say 480watts then you have 480watts/12v=40amps.
 
Each PCI-e connector on the GameXstream is on it's own rail: 12V3 and 12V4.

18A per rail is about twice as much as what you'd actually need for a pair of X1900's.
 
jonnyGURU said:
Each PCI-e connector on the GameXstream is on it's own rail: 12V3 and 12V4.

18A per rail is about twice as much as what you'd actually need for a pair of X1900's.
Click to expand...

Or in the case of independant 12v's :p
 
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