Oversized power supply units

[Hirves]

Been active in computer forums since 1999; been thinking at this lately.

Why in earth and heaven, nowadays' "bob the builders" always choose like a double too powerful PSU?

Please read reviews, add 50W for OC = An ideal PSU.

[Fuzzykins]

Err, what?
The biggest motivation for choosing a higher wattage power supply than necessary is future proof. "I might add another GPU in the future." Stuff like that. Another is that PSU's are most efficient at like 50% ish load.

I agree though, newer computer builders tend to highball PSU's a bit.

[BicycleMafioso]

The 50% myth is a fun one. But I don't get it either really. Get what you need, more watt != more fps.

[Zxian]

Well, yes and no. A 400W no-name brand is still capable of powering my simple i5/i7 machine with a high-mid end graphics card. Would I ever trust it with the ~$1000 or more I have in my computer? Never.

The key thing to look at in power supplies is the quality. 500W Seasonic or Enermax is a far better choice than an 800W noname. JonnyGuru and SilentPCReview are the only two sites that I'd get my PSU reviews from (especially JonnyGuru), since they're meticulous about their testing methodologies. JonnyGuru even goes so far as to disassemble the PSU after testing it in order to inspect the quality of components used and the soldering done to hold the whole thing together.

There's a second matter of efficiency to consider as well. Most PSUs are the most efficient when run at ~40-60% load. The typical i7+6950 or i7+560Ti system will probably draw around 250W from the wall overclocked. Getting a quality PSU such as the Seasonic M12 520W or, even better, the Seasonic X-series will give you all the efficiency, quality and headroom you should need for the average user.

Another reason not to skimp out on your PSU - it's the one component of your computer that can kill every other component in your case. I've seen a system where the PSU decided to go on the fritz, and the only salvagable components were a single stick of RAM and the DVD drive.

[Fuzzykins]

Well, yes and no. A 400W no-name brand is still capable of powering my simple i5/i7 machine with a high-mid end graphics card. Would I ever trust it with the ~$1000 or more I have in my computer? Never.

The key thing to look at in power supplies is the quality. 500W Seasonic or Enermax is a far better choice than an 800W noname. JonnyGuru and SilentPCReview are the only two sites that I'd get my PSU reviews from (especially JonnyGuru), since they're meticulous about their testing methodologies. JonnyGuru even goes so far as to disassemble the PSU after testing it in order to inspect the quality of components used and the soldering done to hold the whole thing together.

There's a second matter of efficiency to consider as well. Most PSUs are the most efficient when run at ~40-60% load. The typical i7+6950 or i7+560Ti system will probably draw around 250W from the wall overclocked. Getting a quality PSU such as the Seasonic M12 520W or, even better, the Seasonic X-series will give you all the efficiency, quality and headroom you should need for the average user.

Wait, what? You lowballed that wattage estimate a bit..

[S7orm]

"Melius abundare quam deficere"

btw mostly because of "possible upgrades"

PSU are a "cheap" part compared to the rest of PC (on mid-high builds) so it's preferred to chose a 100W over the load consumption so you won't have to change the PSU after a year because of CPU upgrades, 2nd graphic card for SLI/Xfire, a sound card you didn't buy because of budget (i did) or another couple of hard disk for music/porns (because we all know 75% of HD space is for torrent shit)

[Fuzzykins]

"Melius abundare quam deficere"

btw mostly because of "possible upgrades"

PSU are a "cheap" part compared to the rest of PC (on mid-high builds) so it's preferred to chose a 100W over the load consumption so you won't have to change the PSU after a year because of CPU upgrades, 2nd graphic card for SLI/Xfire, a sound card you didn't buy because of budget (i did) or another couple of hard disk for music/porns (because we all know 75% of HD space is for torrent shit)

I feel like my sound card will never motivate me to upgrade my PSU...

[Zxian]

250W from the wall means rougly 200W system load. That's actually not that unreasonable for a stock clocked 2600K and 6950 with no other major components (single hard drive/SSD, onboard other stuff). My Q9650@3.4GHz is more power hungry than the 2600K at stock, and my system draws 280W AC when CPU and GPU are loaded with Prime+Furmark.

[Fuzzykins]

250W from the wall means rougly 200W system load. That's actually not that unreasonable for a stock clocked 2600K and 6950 with no other major components (single hard drive/SSD, onboard other stuff). My Q9650@3.4GHz is more power hungry than the 2600K at stock, and my system draws 280W AC when CPU and GPU are loaded with Prime+Furmark.

http://www.legitreviews.com/images/r...onsumption.jpg
http://www.legitreviews.com/article/1488/5/

[Zxian]

That test was done on a system with an i7-970. The LGA1366 CPUs are more power hungry than the LGA1155 CPUs. You can see the graphs for yourself here. (The site has disabled right-clicking to get the image URLs or the source code.... jerks)

Regardless, take any single CPU/GPU system with a build cost of up to $1500, and a quality 500-600W PSU will probably suit you just fine.

[Fuzzykins]

Oh, I completely agree, but I still feel like I won't be recommending any 400W PSU's for normal 2500k/560ti systems in the near future.

[Zxian]

I never said 400W.

The Seasonic X-Series PSUs are some of the nicest power supplies I've worked with. We're talking a ~5mV ripple on the 12V line at full load. sauce

[Fuzzykins]

Mmmm, yes, I know what some of those words mean. x3
No, but seriously, I pretty much toggle between the Seasonic X series and the TX series from Corsair in recommendations. /shrug

[Ghâzh]

Well the 50% efficiency "myth" is mostly true but what most people fails to realise is that your system isn't constantly under load. Not even under moderate load but the most time is spend at idle state actually. Now if you have picked an 800 watt unit for your system which draws 400 watts from the wall under load in hopes of meeting the "golden" 50% efficiency range, you are actually only getting that for the minority of time and mostly you're at 5-15% range where the efficiency degrades greatly .

So yeah, pick an appropriate sized unit if you're conserned by the efficiency. Too little and you'll run in to trouble, too much and you'll run inefficiently. I'm personally not too worried about slightly overdoing it as long as the PSU is quality branded and you aren't paying too much for the extra.

[OlSom]

That test was done on a system with an i7-970. The LGA1366 CPUs are more power hungry than the LGA1155 CPUs. You can see the graphs for yourself here. (The site has disabled right-clicking to get the image URLs or the source code.... jerks)

Regardless, take any single CPU/GPU system with a build cost of up to $1500, and a quality 500-600W PSU will probably suit you just fine.

[Cyanotical]

who has an oversized PSU? nobody buys 1200 watt PSUs

it's not like anyone ever buys a PSU because they think "hey, at some point in the future i may upgrade and i'd rather buy a high power PSU now, so i dont have to find out that my 'just enough' PSU cant handle new GPUs"

[Zxian]

Thanks OlSom.

Cyanotical - I actually bought my PSU for exactly that reason. I managed to get an Enermax Revolution85+ 850W for $200 on sale. Why? Because it's built well, has good efficiency, and has more power capability than anything I'd probably want to shove into a single workstation tower anyways. It's also the only PSU I'll have to buy in the next 3-5 years anyways, unless they significantly change the ATX spec, which I highly doubt.

[BicycleMafioso]

it's not like anyone ever buys a PSU because they think "hey, at some point in the future i may upgrade and i'd rather buy a high power PSU now, so i dont have to find out that my 'just enough' PSU cant handle new GPUs"

That's what I would do.

I also think that it's the way to go. Buy what you need, not what you will never actually bother getting anyway.
Buying more than you need is a bad move. I'd rather buy a PSU that's got identical speccs at 550w than one which is 850w (except the amp on the 12v of c) even if the 550w is more expensive. Becuase it's the better thing to do, and it would last longer.