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Accurate PSU wattage requirement. (Minimum, Recommended)

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July 31, 2012 5:37:29 AM

Hello, this is my first post and since i always come here for answers to tech questions and doubts, i dont always find an exact, to the point answer. I need to know how much PSU wattage I will need for my upcoming build, and more details in the list:

---Intel 3770K 3.5Ghz(turbo boost to 3.9Ghz) i might even overclock it further to possibly 4.2 or 4.3 when i need that extra performance.

--- Asus P8z77-v LK mobo

---EVGA GTX 670 FTW gfx card which is factory overclocked, i might overclock it further, and when the card becomes a bit cheaper i'll throw in another 670 ftw card to put them in SLI and might overclock both occasionally.

---WD caviar blue 1tb HDD @ 7200rpm + 64gb SSD

---basic cd and dvd writer and burner

---nzxt phantom 410 case with 3 fans included and i might add 2-4 more since it can take 7.

---corsair vengeance RAM at 1600MHz (2x4)8gb dual channel

---Cooler master hyper 212 evo heatsink for cpu

I'm planning on a corsair psu @ 850W but im not sure it i need that much or if i will after i upgrade further with SLI and stuff..
I want the PSU to last around 4-5 years so i want to be ready for the sli upgrade and more. I heard that the wattage of a psu decreases by about 10-20% over the course of abot a year. I'm debating between a 750W and 850W both equal quality. I dont want the psu to be at a high load and kept at 50-70% of its wattage capabilities so it doesnt wear out, affect performance, etc. if u need more details feel free to ask me more. and remember i plan to upgrade the gpu and maybe cpu later if needed. i dont care about the price difference as cheaping out to get a 750W might not supply my rig as needed. I want the minimum requirement that would keep the psu at full load and the recommended psu wattage i need that is easy on the psu. and if possible the wattage requirement for each part of hardware for a better understanding on how much i need. even if u guys tell me 750W i'll still be a little doubted so please make solid points to convince me. Thanks so much :) 
a c 111 ) Power supply
July 31, 2012 5:42:42 AM

A 650W power supply will be able to power the whole system.

I would also change your board.
a c 76 ) Power supply
July 31, 2012 5:48:28 AM

People tend to freak out about wattage requirements and WAY overestimate what's really needed. Most of the time, you don't really need anywhere near the amount of wattage you might think you do.

Here's a good wattage calculator. http://extreme.outervision.com/psucalculatorlite.jsp

It overestimates a bit itself, and I'll go ahead and add onto it's estimate that I got from it for your system as well, and recommend a good 650-750W unit.

850W is definitely WAY overkill. You DO NOT need 850W.
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July 31, 2012 5:49:23 AM

But the card when overclocked is about 200watts and when I put it in sli with both overclocked it needs 230 watts more 650+230= 880W :S so from my nooby understanding id be pushing an 850W psu hard. And what's wrong with the mobo Im pretty sure it's compatible and it looks like a good one but please feel free to let me know before I buy it and regret it
a b ) Power supply
July 31, 2012 5:50:03 AM

If you're planning on overclocking you should get something more than a P8Z77-V LK, at least a P8Z77-V Pro.

As for power delivery, 650 will be enough for that machine but it would be cutting it close for SLI/Crossfire.

If you want a good 750-850 watt PSU then the SeaSonic X-Series will work fine.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Really can't go wrong.

If that looks remarkably similer to the Corsair AX850 below that's because the AX850 is manufactured by SeaSonic and it's damn near the same power supply!

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
July 31, 2012 5:50:20 AM

Did u guys consider my extra 2-4 fans and another 670 in sli upgrade in a few months??
a c 76 ) Power supply
July 31, 2012 5:52:02 AM

MoeThePro said:
But the card when overclocked is about 200watts and when I put it in sli with both overclocked it needs 230 watts more 650+230= 880W :S so from my nooby understanding id be pushing an 850W psu hard. And what's wrong with the mobo Im pretty sure it's compatible and it looks like a good one but please feel free to let me know before I buy it and regret it


You'll probably pull 600-650W AT THE MOST with both GPU's AND the CPU OC'd and all 3 maxed out at 100% usage.

And fans pull almost literally NO power. Not even a concern.
July 31, 2012 6:06:56 AM

Well to be honest I'm not the overclocker person in general except once in a while when I wanna try the game in a higher setting to see how it looks in for example in ultra.. And when I do I put the fans in a very high rpm and I don't do extreme overclocking only slight like to 4.1Ghz at most and gpu same thing I just over exaggerated the overclock to make sure nobody gives under-wattaged psu suggestions that would be at 100% load and btw is this mobo still fine for very slight overclocks? And dj please if u can divide the power requirements for the parts please since I'm still doubted sorry bout that though :/ 
a c 76 ) Power supply
July 31, 2012 6:14:10 AM

To be honest, I don't quite have the knowledge to be able to break the wattage down component by component, I'm just going off of everything that I've ever seen in power usage reviews.

You can search them up for yourself to see, but you'll see that max wattage very rarely, if ever, actually gets to 700W, even on the most power hungry 2-Way SLI/CF systems (which a 3770K ISN'T a power hungry CPU and 670's aren't power hungry GPU's either. Both very efficient, compared to previous generations).

But yes, a P8Z77-V LK is OK for a small OC.

I would honestly recommend this though. Cheaper and better for OC'ing too. ASRock Z77 Extreme4 LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard
July 31, 2012 6:16:27 AM

DJDeCiBeL said:
You'll probably pull 600-650W AT THE MOST with both GPU's AND the CPU OC'd and all 3 maxed out at 100% usage.

And fans pull almost literally NO power. Not even a concern.

Well to be honest I'm not the overclocker person in general except once in a while when I wanna try the game in a higher setting to see how it looks in for example in ultra.. And when I do I put the fans in a very high rpm and I don't do extreme overclocking only slight like to 4.1Ghz at most and gpu same thing I just over exaggerated the overclock to make sure nobody gives under-wattaged psu suggestions that would be at 100% load and btw is this mobo still fine for very slight overclocks? READ FROM HERE if u don't know much about overclocking.. And dj please if u can divide the power requirements for the parts please since I'm still doubted sorry bout that though
July 31, 2012 6:17:37 AM

Oh nvm thought u guys left my post sorry for the repost
July 31, 2012 6:20:03 AM

Thanks ill check out that mobo but I'll most probably stick with asus

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a c 76 ) Power supply
July 31, 2012 6:24:11 AM
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Also, check this page out. http://www.guru3d.com/article/geforce-gtx-670-2-and-3wa...

They recommend a 700W PSU for SLI 670's.
July 31, 2012 6:31:04 AM

It mentioned they recommend 700W minimum so to me that means with a 750W psu it'd be pushing at about 80% load
July 31, 2012 6:32:01 AM

Thanks for staying with me and sorry if I'm taking too much of ur time Im greatly appreciating ur help
July 31, 2012 6:37:44 AM

Best answer selected by MoeThePro.
a c 76 ) Power supply
July 31, 2012 6:38:55 AM

MoeThePro said:
Thanks for staying with me and sorry if I'm taking too much of ur time Im greatly appreciating ur help


No problem. :) 

And trust me, if i didn't TRULY believe that 700-750W was enough, I wouldn't recommend it.
July 31, 2012 6:43:12 AM

Now I'm convinced, btw last question and I'm done how much load will be on the psu after the sli upgrade approx
a c 76 ) Power supply
July 31, 2012 6:46:26 AM

MoeThePro said:
Now I'm convinced, btw last question and I'm done how much load will be on the psu after the sli upgrade approx


At max load (100% for the CPU and both GPU's, which NEVER happens, BTW) with a 750W PSU, I'd say it would be around 70-80%, at the absolute most. Nowhere near really stressing it if it's a good unit.

In general gaming usage, probably closer to 50-65%, and just normal non-gaming usage 20-30%.
a b ) Power supply
July 31, 2012 11:25:58 AM

This topic has been closed by Mousemonkey
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