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**Praetor** · 04-02-2005, 01:49 AM

Section 05 - VFAQ
How many Watts Do I Need??
The answer is dont ask that question. That's right. Don't ask that question. Why not? Because it's almost pointless. Why? If you read the section where I described how to pick a good PSU (hint hint) then you'd know what to look for. A recap (or should I say, introduction?

)

Make sure the PSU has, at the absolute least, 18A on the 12V line. In reality, given what you can get for the money you spend, you should set this bar at 24A. If you need suggestions or inspiration, see the above suggestions
Make sure the PSU has 16ms or better hold-up time. Just because a PSU seems to have decent numbers everywhere else doesnt mean there's no catch. This is an example of such a scenario -- the PSU has the minimum 18A on the 12V line and is SLI Certified and all but only has 12ms hold-up. Dont get it!
With the above two points in mind as a minimum (more points in the section detailing how to pick out a good PSU), when you pick a PSU that matches those criteria you'll end up with "a healthy number of watts" so dont stress it (i.e., there is no 250W PSU or whatever with the above characteristics). So just match the 12V rail and the hold time and for the most part you'll be ok
Now if you've read the above and you're absolutely dying still to get a number (because for some reason, you think a big number in the watts column is going to give you performance, then use 450W.

Is my PSU strong enough for my setup?
Again, see the above FAQ, this is just a rehash of the same thing. More particular however, make sure you spend an appropriate amount of money on the PSU as you do the rest of the system How much is appropriate? Common sense! For instance, if you're spending $1000 on some fancy SLI configuration and you're buying a $30PSU, something's not gonna work so well. Here is a very rough ballpark guide:
- Low end videocard ... shoot for 24A (to a absolute minimum of 18A)
- Midrange single videocard ... shoot for 28A
- Midrange dual-videocard ... shoot for 32A
- High-end setups (any) ... shoot for 34A+
It seems like stringent requirements/guidelines but once you start looking at the products you'll quickly realize it's not that unaffordable.

I have a SLI/Crossfire setup ... does this mean I need a SLI/Crossfire certified PSU?
No. Just get a PSU with a sufficient enough number of amps on the 12V line and you'll be fine! If you reall insist on and want a number, I reccomend 34A as a minimum for two GPU and 38A as a minimum for quad-GPU.

04-02-2005, 01:49 AM	#6 (permalink)
Praetor Administrator Join Date: Jul 2004 Location: Canada Age: 24 Posts: 19,943	Section 05 - VFAQ *How many Watts Do I Need??* The answer is dont ask that question. That's right. Don't ask that question. Why not? Because it's almost pointless. Why? If you read the section where I described how to pick a good PSU (hint hint) then you'd know what to look for. A recap (or should I say, introduction? ) Make sure the PSU has, at the absolute least, 18A on the 12V line. In reality, given what you can get for the money you spend, you should set this bar at 24A. If you need suggestions or inspiration, see the above suggestions Make sure the PSU has 16ms or better hold-up time. Just because a PSU seems to have decent numbers everywhere else doesnt mean there's no catch. This is an example of such a scenario -- the PSU has the minimum 18A on the 12V line and is SLI Certified and all but only has 12ms hold-up. Dont get it! With the above two points in mind as a minimum (more points in the section detailing how to pick out a good PSU), when you pick a PSU that matches those criteria you'll end up with "a healthy number of watts" so dont stress it (i.e., there is no 250W PSU or whatever with the above characteristics). So just match the 12V rail and the hold time and for the most part you'll be ok Now if you've read the above and you're absolutely dying still to get a number (because for some reason, you think a big number in the watts column is going to give you performance, then use 450W. *Is my PSU strong enough for my setup?* Again, see the above FAQ, this is just a rehash of the same thing. More particular however, make sure you spend an appropriate amount of money on the PSU as you do the rest of the system How much is appropriate? Common sense! For instance, if you're spending $1000 on some fancy SLI configuration and you're buying a $30PSU, something's not gonna work so well. Here is a very rough ballpark guide: - Low end videocard ... shoot for 24A (to a absolute minimum of 18A) - Midrange single videocard ... shoot for 28A - Midrange dual-videocard ... shoot for 32A - High-end setups (any) ... shoot for 34A+ It seems like stringent requirements/guidelines but once you start looking at the products you'll quickly realize it's not that unaffordable. *I have a SLI/Crossfire setup ... does this mean I need a SLI/Crossfire certified PSU?* No. Just get a PSU with a sufficient enough number of amps on the 12V line and you'll be fine! If you reall insist on and want a number, I reccomend 34A as a minimum for two GPU and 38A as a minimum for quad-GPU. __________________ ASUS P5K Premium WiFi-AP, Q6600@3.7 / ASUS P5ND, E6400@3.8 4GB OCz Platinum XTC 8500 / 4GB CorsairXMS2 6400 5x500GB Seagate 7200.10 / 2x500 Seagate 7200.10 OCz 8800GTX 768MB @ 630/800 / 2x Galaxy 8800GT SLI Last edited by Praetor; 07-14-2006 at 06:54 PM.