Time to build a new rig...

[juneau]

There are a few cards out there that will run safely on less than 20A's due to the overrated draw by Nvidia and Ati. It's just depends on the PSU.

I actually know of a few people running 8800GT's on low powered PSUs but mainly in Shuttle builds.

@WT: Overkill on the PSU huh? Err, why?

[WalkinTarget]

Juneau, I posted this in another thread somewheres around here, but rather than search for it, I'll post the relevant info from a JohnnyGuru thread and let you read it from a guy who designs these things for a living:

What is “efficiency”?

Efficiency is the ratio between the useful output of an energy conversion device and the input. For example, if your computer uses 300W, but pulls 400W from the wall, then the efficiency is 300W/400W, or 75%.

Computer power supplies are typically 75% efficient, especially those units included with computer chassis or units made more than a couple of years ago before power supply efficiency was made such a priority. The BFG GS, LS, MX and ES power supplies are typically 80% efficient or better.

Why is efficiency important?

Quite simply, if your power supply is more efficient, your computer will use less power. Depending on how much you pay for power from your utility company and how much power your computer typically uses, you can save anywhere from $1 to $10 per year, per computer… perhaps more! Furthermore, because any AC power that is NOT converted into DC power is exhausted as heat, a more efficient power supply inherently runs cooler. Not only does this mean your office is going to be cooler, but also allows the power supply manufacturer to use a slower, quieter fans to cool the power supply.

Aren't higher wattage units less efficient at lower loads?

With all things being equal, yes. But you can't always compare brand A with brand B and assume that because brand B is a higher wattage that it's going to be less efficient at lower loads.

It is true that most power supplies are only at their most efficient when the load on them is 20% or more of their capability. So with conventional power supplies, you pretty much have to throw any kind of green initiative out the window when trying to buy a power supply that will allow for future expansion; like buying a second graphics card for SLI or adding more hard drives to run a RAID array.

Of course, even conventional power supplies vary from unit to unit, and since the initiative to be more efficient is a relatively new concept be aware that even if a modern day computer power supply is only 80% efficient from loads of 20% and up, it may be 77% or 78% efficient at a 10% load and this may still be much more efficient than the power supply you're replacing, even at it's best efficiency!

What is the "wattage" number (i.e. 650W, 800W, etc.) actually telling me?

When you see the wattage rating of a power supply, you’re seeing the total maximum output capability of that particular power supply, but a computer has multiple voltage needs, and newer computers require more of the power supply’s capability to be on the +12V DC output rail. CPU’s and GPU’s regulate their power off of the +12V DC rail. Also, all of the computer’s motors run off of +12V DC: hard drive and optical drive motors, fan motors, pumps for water-cooling, etc. It wasn't too long ago that graphics cards did not require auxiliary +12V power and CPU's use to regulate their voltage from the +5V rail. An older power supply may have a lower percentage of it's power on the +12V than a more current unit.

What is the difference between "continuous" and "peak" ratings?

Some power supply units are rated for continuous output while others are rated at peak. "Continuous" means that the power supply is rated to run at it's maximum capability for no pre-determined period of time, while "Peak" indicates that the power supply will only run at the specified wattage for a brief period of time, possibly only a few seconds or up to a minute. This number is typically about 100W more than the power supply's actual continuous rating.

How does the temperature inside of my case affect the performance of my power supply?

Power supplies can perform differently depending on the temperature at which they are operating at. When a power supply is rated for it's total output wattage, it is rated to do so at a particular temperature. Anything beyond this temperature may take away from the power supply's capability. A power supply that is rated to put out 550W at 25?C or 30?C (room temperature) may only be able to put out 75% of that at 40?C or 50?C (actual operating temperature). This difference is called the "de-rating curve". A normal operating temperature for a power supply is 40?C.

OK, back to WT now - This last one is one I will stress, and I always assume the PSU will be running under less than ideal conditions due to a warm case.

[juneau]

Juneau, I posted this in another thread somewheres around here, but rather than search for it, I'll post the relevant info from a JohnnyGuru thread and let you read it from a guy who designs these things for a living:

What is “efficiency”?

Efficiency is the ratio between the useful output of an energy conversion device and the input. For example, if your computer uses 300W, but pulls 400W from the wall, then the efficiency is 300W/400W, or 75%.

Computer power supplies are typically 75% efficient, especially those units included with computer chassis or units made more than a couple of years ago before power supply efficiency was made such a priority. The BFG GS, LS, MX and ES power supplies are typically 80% efficient or better.

Why is efficiency important?

Quite simply, if your power supply is more efficient, your computer will use less power. Depending on how much you pay for power from your utility company and how much power your computer typically uses, you can save anywhere from $1 to $10 per year, per computer… perhaps more! Furthermore, because any AC power that is NOT converted into DC power is exhausted as heat, a more efficient power supply inherently runs cooler. Not only does this mean your office is going to be cooler, but also allows the power supply manufacturer to use a slower, quieter fans to cool the power supply.

Aren't higher wattage units less efficient at lower loads?

With all things being equal, yes. But you can't always compare brand A with brand B and assume that because brand B is a higher wattage that it's going to be less efficient at lower loads.

It is true that most power supplies are only at their most efficient when the load on them is 20% or more of their capability. So with conventional power supplies, you pretty much have to throw any kind of green initiative out the window when trying to buy a power supply that will allow for future expansion; like buying a second graphics card for SLI or adding more hard drives to run a RAID array.

Of course, even conventional power supplies vary from unit to unit, and since the initiative to be more efficient is a relatively new concept be aware that even if a modern day computer power supply is only 80% efficient from loads of 20% and up, it may be 77% or 78% efficient at a 10% load and this may still be much more efficient than the power supply you're replacing, even at it's best efficiency!

What is the "wattage" number (i.e. 650W, 800W, etc.) actually telling me?

When you see the wattage rating of a power supply, you’re seeing the total maximum output capability of that particular power supply, but a computer has multiple voltage needs, and newer computers require more of the power supply’s capability to be on the +12V DC output rail. CPU’s and GPU’s regulate their power off of the +12V DC rail. Also, all of the computer’s motors run off of +12V DC: hard drive and optical drive motors, fan motors, pumps for water-cooling, etc. It wasn't too long ago that graphics cards did not require auxiliary +12V power and CPU's use to regulate their voltage from the +5V rail. An older power supply may have a lower percentage of it's power on the +12V than a more current unit.

What is the difference between "continuous" and "peak" ratings?

Some power supply units are rated for continuous output while others are rated at peak. "Continuous" means that the power supply is rated to run at it's maximum capability for no pre-determined period of time, while "Peak" indicates that the power supply will only run at the specified wattage for a brief period of time, possibly only a few seconds or up to a minute. This number is typically about 100W more than the power supply's actual continuous rating.

How does the temperature inside of my case affect the performance of my power supply?

Power supplies can perform differently depending on the temperature at which they are operating at. When a power supply is rated for it's total output wattage, it is rated to do so at a particular temperature. Anything beyond this temperature may take away from the power supply's capability. A power supply that is rated to put out 550W at 25?C or 30?C (room temperature) may only be able to put out 75% of that at 40?C or 50?C (actual operating temperature). This difference is called the "de-rating curve". A normal operating temperature for a power supply is 40?C.

OK, back to WT now - This last one is one I will stress, and I always assume the PSU will be running under less than ideal conditions due to a warm case.

I still don't think that people need to go out and buy a 800W PSU with 50A on the 12V when a good lower powered PSU will do. I'm still running my 520W PSU and i plan to for quite a while. Unless of course Gfx card power consumtion goes further through the roof than it already has. I've read quite a bit about case temps and it doesn't actually make as much difference as they're making out. That's the worst case scenario.

The only thing that concerns me is that all PSU slowly lose their efficiency and power over time, but if you don't skimp on what PSU you buy then it won't cause too many problems.

[WalkinTarget]

Juneau, we have yet to determine what the +12 rail will even supply on this barebones PC, so that should be the place we start from.

You know I would never recommend an 800w unit for this one. I myself would even lowball suggest a Coolmax 400w for $20 (AR) from the Egg if you really want a budget PSU.

[juneau]

I just had a quick flash of thought. Doesn't the 9800GT require less power than the 8800GT? I'm sure one of the things they did was to tweak the power usage.

[bobytt]

Kids , i have wonderful article for you
AnandTech: The Cost of Running Your PC

[WalkinTarget]

for a reply from Gene on this one .. its up to him .. Juneau and I will just take this offsite and settle it by fisticuffs.

[juneau]

for a reply from Gene on this one .. its up to him .. Juneau and I will just take this offsite and settle it by fisticuffs.

Can i bring a knife?

[{CLR}geneSW]

for a reply from Gene on this one .. its up to him .. Juneau and I will just take this offsite and settle it by fisticuffs.

Again, this isn't going to be a powerhouse computer. Simply enough to play Sims 3 when it comes out will be more then enough.... I was thinking along the lines of a 500w psu and maybe a AMD 5000+ or 5200+...

[juneau]

Again, this isn't going to be a powerhouse computer. Simply enough to play Sims 3 when it comes out will be more then enough.... I was thinking along the lines of a 500w psu and maybe a AMD 5000+ or 5200+...

Corsair VX 450W.

[Ghost_Rain]

You can Now Buy thr AMD 6000 Cpu pretty Cheap these days

[{CLR}geneSW]

You can Now Buy thr AMD 6000 Cpu pretty Cheap these days

Yes, but I can get a 5000+ cheaper, and she doesn't need that much power.