Why do people always go overkill on their PSU Wattage?

Do you have any idea why people go for things like 1000w PSU's in their builds?

I mean I have a 650w PSU and that's way more than my computer uses. I can throw in another 7970 and still be around 100w over the recommended amount...

I mean as long as it has a high effiiciency why go to such high amounts?

 

My specs:

Specs:
i5-3570k @ 4.2GHz
Samsung 830 128gb SSD
XFX Radeon 7970 Black Edition 3GB @ 1100MHz
8gb GSkill Sniper RAM @ 1866MHz
Z77x-UD3H Motherboard
Hyper 212 + Heatsink
NZXT Phantom 410 Case
Corsair Professional HX650w Power Supply - 80+ GOLD

 

1000w, I'm not sure why people do that to be honest.  I went high on mine just to give myself some headroom when it comes to upgrading.

Mine is 750w, but I did that on purpose because I have tons of case fans and about 10 different USB devices that need to be powered.  I figure with the 750w I'll be safe, even if I decide to add a second graphics card.

On my last build I went with the recommended PSU.  In the long run, it screwed me over because I had to buy a new one before I could upgrade my GPU.  So I guess people just do it to avoid feeling like a dumbass (like I did, lol).

I went with a 1000w psu cause my plan(which did not end up happening)was to down the road add 1 or 2 more 7970's,plus i was going to max out the HD space in my case,and i wanted to make sure i had enough plus i got mine on sale for like $100,and it's i brand i decided to trust cause i saw linus use a 650w(from the same maker) on his test bench in some older videos.

2 OCd 7970s, OCd 2600k, Sound card, 5 HDDs.... 1kw isn't that overkill at that point.

Just tested, I can pull over 800w

A very valid point you have there...

[IMG]http://i.imgur.com/tonol.png[/IMG]

Prime95 and Furmark running on my 3570k @ 4.6GHz and MSI PE 670

That's measured from my UPS. Which has 2 monitors (50w total) and an idle RAID10 array (don't know the wattage of the array)

So I'd say my PC uses ~450w max... I have a 650w PSU

i lol'd @ the remaining battery runtime

Aside from the reason Scrap pointed out. The reason I decide from is this,(provided you know what you are doing and not just buying it because it has a bigger number hurrdurr)

Energy efficiency, you can have that 600w powersupply, and you can even have an extra GPU thrown in there and have it run it just fine. But did your efficiency go down? Your computer doesn't have to crash in order to tell you that your psu isn't good enough or is working harder than it should to power your machine.

Lets just say that you were slightly under maximum efficiency, 6 months later the quality and amount of power your psu feeds your machine would dwindle based on how you treated it to begin with. Have to much headroom (1000w psu for an mid-tower) and the feeding could be so underwhelming that your psu is working harder to convert and feed the power comming from your socket than actually providing it to the rest of your machine. Have too little, and you will overwork it to death.

 

But personally. I have an AX1200i. Reason being my spec for one, 2 690 OC, 3970 OC, Xonar STX, revodrive, a wackload of HDDs, 3 ASUS proart IPS displays etc. But also as my main studio machine it is running truly 24/7, constantly running some kind of demanding program when I am not using it directly, and constantly recieving and sending files all over the place.

With the configuration that I have personally, the AX1200i is at "peak" efficiency on its standard, and I expect it to continue to run at "peak" efficiency indefinitely because of the extra precautions. Having a UPS helps as well for it not only 'cleans' the power comming from your wall (extending the psu lifespan) but some also migitates the amount of power your psu even recieves to get the absolute most out of it and reducing the normal load.

 

But more times than not people really do overbuy on power supplies. It can actually HARM your comptuer.

I have a SeaSonic X650 Gold that I got for free. I think it's about perfect for my rig.

I know what you're saying about efficiency  Iirc, PSU's are most efficient at around 50% load. I think the perfect PSU (not assuming buying for future upgrades) would be 75w-100w over the actual PC usage. This should leave your day to day usage, between idle and load, at around 30%-50% of the full output of the PSU. Therefore keeping it in the best efficiency range during most of your usage situations... My % might be wrong, but I hope you understand what I'm trying to say.

 

I meant you want your PSU to be between 30-50% load w/ your daily usage, but still be large enough not to max out when everything is pushed balls to the wall. And I could probably get away with a 550w with my system.

Exactly.

1300w psu for a system that only uses around 450w personally, i just did it to have some head room, was gonna get a 800w but nabbed a 1300w on sale