External Power Supplies?

C

canis

Limp Gawd
Joined
Jul 8, 2005
Messages
154
I for one would like to see the comeback of external power supplies for video cards, now that the current cards are drawing over 300+ watts of power. I sometimes wish that I could just have a power brick for my video card rather than taxing my 450 Watt supply even further or forcing me to upgrade to a 600W+ PSU.

To me, taking such a large strain off the system PSU should increase stability and allow a smaller main PSU, reducing noise and case temperatures. I also think that a dedicated power supply for the video card would supply cleaner and more stable power, allowing higher overclocks (though I could be wrong).

I wouldn't mind one more cable coming out the back of my case, if it meant that my video card and system would be more stable. Also, it would make upgrading a slightly older system easier, because the case and power supply could be retained (because they would only be powering the new processor and hard drives.
 
If they come out with a X1900 based version of that, I am all over it!

Thanks.
 
canis said:
I for one would like to see the comeback of external power supplies for video cards, now that the current cards are drawing over 300+ watts of power.
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Current cards are not drawing 300W of power. The fastest are drawing around 100W of power (each). The PSU's AC to DC efficiency raises the power draw from the wall, but that's the same for any device plugged into a regular PSU.
 
There are pluses and minus to that. I'd think that using external power supplies would eat more power and add more clutter, though I would save on having a poweful PSU. I wonder how hard it would be to have a connector for both external power and keeping the PCI power connector. That way, one could chose, and if they needed an external power supply, they could pick one up if needed, keeping the cost of it out of the standalone card.
 
it seems to be a common idea that people need 600w PSU just to run their systems. in some situtaions this is true but for the most part your not using near as much as you think. currently my PSU draw is 103-110w for my entire system. now im not running a high end graphics card or even a high end cpu but i do have alot of other stuff that im sure comes close to the same or slightly under it.

from what i can tell it seems people are reading the manuals of their cards and see they suggest a 350w PSU or higher depending on the card and then assume anything less wont work. the numbers listed in the manuals are just a guideline. basically the idea is for the card makers to over estimate the power draw so they dont have a bunch of complaints if someone doesnt have enough ower for their system. for the average person your looking at less than 350w for the system, but you want to make sure your not buying a cheap POS PSU that doesnt have proper voltage. usually if you buy name brand around the $80-$150 range your good to go, but it doesnt hurt to read some reviews just in case.
 
I think I read somewhere that development fo the 7800GTX at one point had external power supplies but they were able to make draw less power thus discarding that.
With the quad sli Dell Renegade setup there is a seperate power adapter for reach dual card, so I would be surprised if the 7900 card refresh would NOT have a seperate power adapter.

What I like about extern psu for video cards is the releaxed load on the main psu, I just hope that the power bricks will be situated seperate from the wall plug.
 
the 7900GTX shouldnt need a power brick since its using 90NM which will draw less power but the power brick would need a locking clip to the GFX to reduce chance of accidently knocking out the power during a game :eek:
kuyaglen said:
What I like about extern psu for video cards is the releaxed load on the main psu, I just hope that the power bricks will be situated seperate from the wall plug.
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omfg i hate the transformers right on the plug. takes up like 3 spots on your power bar
 
Dark_fire said:
the 7900GTX shouldnt need a power brick since its using 90NM which will draw less power but the power brick would need a locking clip to the GFX to reduce chance of accidently knocking out the power during a game :eek:
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Yeah the die is shrinking, but the transistor count is going up considerably, so the power consumption is probably going to increase, if only a little, but maybe not.

The new Pentium 65nm Presler are drawing more power than the 90mn P4 for instance.
 
CEREAL_KILLER said:
it seems to be a common idea that people need 600w PSU just to run their systems. in some situtaions this is true but for the most part your not using near as much as you think. currently my PSU draw is 103-110w for my entire system. now im not running a high end graphics card or even a high end cpu but i do have alot of other stuff that im sure comes close to the same or slightly under it.
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to wit:

drift3.gif


Chart by Oleg Artamonov

the reason you see such monster supplies these days is that they need to cover multiple specs for backward compatibility, thus the vast majority of power goes unemployed
thats not the same as saying a modern supply will not be optimized to deal with a typical modern config because they generally are, which is why the spec keeps changing to reflect the current needs of the components

L0s7 4 Lyf3 said:
Yep, you read the title I have a question about powering CPU's...

What reasons did CPU makers have to switch power draw over to the +12V Rail? What advantages does it have over +3.3V or +5V?
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gee said:
lots of reasons.

The main one is current - if you have a CPU pulling 100W on a motherboard, the Vcore regulator will pull >20 amps from the 5V rail. This is a lot of current to move around... at 12V, the current required is >8.3A - less than half. >20A requires thick PCB traces, heavy cabling, and so on.

You can more efficiently make a power supply that produces low current at high voltage, than a power supply that produces high current at low voltage. So your computer's PSU runs a bit cooler and draws less power from the wall.

And load regulation became an issue - lots of stuff in your computer (PCI cards, hard drive controllers, USB devices) run on 5 volts, and the 5V rail has to be stable. In your average linux box with a Prescott, your computer's CPU changes its power demand from 10W to 100W hundreds of times a second! and this causes immense current swings on the 5V rail, causing it to "jump around", possibily making your computer unstable. Few things in a computer require that the 12V rail is steady - normally it's just used for electromechanical things (fans, hard drive spindles, etc) which don't care if they're getting 10V or 14V. So moving the CPU regulator there made sense, since it keeps crap off the 5V rail.
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gee is our resident EE BTW
and to add to L0s7 4 Lyf3 question PCI-E is all +12V

adding externals especially if they are linear regulated supplies as opposed to switch mode adds horribly to the inefficiency though they would be far better regulated than a cheap switch mode power supplies (refered to as an SMP)

but a single well regulated SMP is a far more elegant solution
in the full scientific meaning of its use

a modern ATX12V v2.0 supply with dual +12V rails or a modern EPS12V supply with 3 to 4 +12V rails to isolate +12V fluctuation is still by far the best solution and one Id highly encourage
(youd only want an EPS12V split rail (x4) config if you where running a dual CPU setup)


watts dont mean much these days, rather its the amps per rail and just as importantly how the supply was originally rated, unfortunately there really is no established proceedure to compare supply to supply and many a "300W" will kick the dogsnot out of 500W supplies

read up over in the PSU forum a bit ;)
 
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