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PCI-E Power Requirements

V

VT-Vincent

n00b
Joined
Dec 2, 2003
Messages
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I'm currently building a new system, and I'm curious about the +12V PCI-E power requirements for some of the higher-end graphics cards. I'm seeing that a lot of them require a rating of 20A or higher, but most of the power supplies I have been looking at usually have two PCI-E connections, both rated lower than that. For example, the ST50EF-Plus is rated for 18A on both of it's PCI-E connectors, so does this mean it wouldn't support a card requiring 20A?

I'm confused. :confused:
 
Can you post a link to an example card? I'm guessing 20A is for the requirements of the whole system, not just the card.
 
Okay. That 26A is what they're recommending for that card, plus a motherboard, CPU, hard drives, memory, blinkenlights, and all that. Here's an excerpt from another, similar card:
Minimum of a 400 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amp Amps.)
Minimum 500 Watt for SLI mode system.
(Minimum recommended power supply with +12 Volt current rating of 28 Amp Amps.)
An available 6 pin PCI-E power connector (hard drive power dongle to PCI-E 6 pin adapter included with card)
Click to expand...
So this says it wants 18A for system+1 card, or 28A for system+2 cards. Probably a bit excessive for the cards (and a bit on the low side for system draw) but it yields 10A per card and 8A for the rest of the system. So your multi-rail PSU with 18A per pci-e connector is fine - one will have the system and one card on it, and the other will have the other card on it.
 
Many GPU marketers under-estimate PSU requirements for 3 reasons:

(1) Increased sales, as they will sell fewer GPU's if they require a new PSU.

(2) No OC'ing is taken in to consideration.

(3) They based on an "average" system, where as most people buying highend GPU's also have more RAM, HDD's &
a higher performance CPU, plus other "non-average" parts.

At this time I recommend a minimum of +12V@26A for a single GPU & +12V@34A for dual GPU's & more is always better!

We may soon see much higher requirements as the new DX10 GPU's come to market. :eek:
 
David, by your recommendation, does that mean the ST50EF-Plus would be insufficient for a single GPU system? Should I be counting the +12V of that power supply as 36A or 18A? :confused:
 
Very good... While on the subject of the ST50EF-Plus, do you beleive it would be sufficiant for the following system?

Intel Core 2 Duo 6300
Intel 965G Motherboard
4GB PC2-667 Memory (4x1GB)
eVGA or XFX GeForce 7900GT Video Card (Single card, no SLI)
2 Western Digital Serial ATA Hard Drives
Soundblaster Audigy 2 Platinum
Antec NSK4400 Case

Also, does anyone have an opinions on the power supply iteslf?
 
VT-Vincent said:
Very good... While on the subject of the ST50EF-Plus, do you beleive it would be sufficiant for the following system?

Intel Core 2 Duo 6300
Intel 965G Motherboard
4GB PC2-667 Memory (4x1GB)
eVGA or XFX GeForce 7900GT Video Card (Single card, no SLI)
2 Western Digital Serial ATA Hard Drives
Soundblaster Audigy 2 Platinum
Antec NSK4400 Case

Also, does anyone have an opinions on the power supply iteslf?
Click to expand...
No problems & this Enhance built PSU should be a very good quality PSU. ;)
 
Any reason why you've picked the NSK4400? The NSK6500 is a little bigger and gives you a quieter front-intake solution.
 
I work for an electronics retailer which carries the NSK4400, which means employee discount. Same with the processor and board, Intel accomodation. :D
 
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