Newbie Power Question

S

Stubborn

New Member
I just recently purchased a new PC and I'll be upgrading it Friday with a GeForce 7800 GT and a Creative XFI Fatal1ty but I'm not sure if I need to upgrade the PSU. The specs for the stock PSU are as follows:

Hipro 300-Watt 24-Pin ATX Power Supply


General Features:
300-watt
One (1) 9-inch 24-pin ATX power connector
One (1) 4-pin Aux power connector
Five (5) 4-pin molex power connectors
One (1) floppy power connector
Two (2) SATA power connectors


Power Specifications:
300-watt max output
+3.3V, 18.0A
+5V, 25.0A
+12V, 19.0A
-12V, 0.8A
-5V, 0.25A
+5Vsb, 2.0A
I don't quite know what all of this really translates to because I just started my learning about this stuff 5 minutes ago when I read the PSU 101 sticky.
I know the amperage is what I need to worry about but it got me wondering becaues the new video card says it requires 350w and this thing I have is only max 300.

I'll be running logitech's Z-5450 speakers along with this new 7800 GT card so I really don't want to dick around with a weak PSU.

I'd appreciate any opinions on this matter and please talk to me like the newbie that I am. The most I've ever done is upgrade some RAM.
 
"Minimum of a 450 Watt power supply"

That's what it says on Newegg when I checked the requirements of a GF7800GT. So your current PSU isn't good enough for that card and I would recommend getting a PSU with atleast a total of 25A on the +12V rail. Atleast, more would be better.
 
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I think I have it figured out. What I'm looking for it the 12V rail for my video card, I guess....and what I have is 12x19=228. That's not enough. So I should be looking for something that is 12v and around 30A. But then what about the speakers? I'll need some serious power for them too, I assume, and then all the 5v and 3.3V for the little guys. So basically I need about 800watts, right........ or do the sound cards act as an amp allowing me to run a smaller rail on it?
 
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mrjack said:
"Minimum of a 450 Watt power supply"

That's what it says on Newegg when I checked the requirements of a GF7800GT. So your current PSU isn't good enough for that card and I would recommend getting a PSU with atleast a total of 25A on the +12V rail. Atleast, more would be better.
Click to expand...

That's what I figured. Thanks for the help. 450 Watts on a video card is some serious business. I didn't even have that much pushing two JL 12w0's. Yikes.
 
But then what about the speakers? I'll need some serious power for them too, I assume, and then all the 5v and 3.3V for the little guys. So basically I need about 800watts, right........ or do the sound cards act as an amp allowing me to run a smaller rail on it?
Click to expand...
You do NOT need 800W. The speakers do not draw their power from the computer. That is why they are plugged into a power point. All that the sound card provides is a signal voltage. A 450-500W power supply with a strong +12V rail would be fine, take a look at PSU101 for some recommendations.
 
Ah, sweet. I knew the wireless speakers were plug-ins, but I thought the rest were run off the PC (just like regular old speakers). That helps a ton, thanks.

I think I have one last question. If I go with something that has twin rails, like 12V1@18A, +12V2@18A for example, would I somehow plug both into my video card, or do I plug only one and make sure the other one remains unused?
 
Only one of the rails gets used powering the video card. Do not worry that the single rail does not meet the requirement of the video card, as the requirements you read are not what the video card itself requires, but what a system using that video card should require (and the other rail will be used powering other components).

If your PSU has dual rails, one rail will power the CPU & mobo, while the other will power everything else.
 
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I got a question then, if my psu has 2-6 pin connectors for PCIe, and 2 12v rails, what does the other 12v rail do that's not plugged into mobo?
 
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