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 Post subject: What PSU Wattage Should I Get?
PostPosted: Thu Aug 07, 2014 6:04 pm 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
Posts: 6
Hello all,

I'm currently in the process of acquiring parts to build my first gaming PC. I've been using PSU calculators around the Internet but different sources give me different results. I was hoping someone here could better advise me.

My proposed parts list is as follows :

CPU : Intel Core i5-4590 Haswell Quad-Core 3.3GHz LGA 1150 84W Desktop Processor Intel HD Graphics 4600

GPU : Gigabyte R9 270X GDDR5-2GB 2xDVI/HDMI/DP OC Graphics Card

Motherboard : Gigabyte GA-Z97X-SLI LGA 1150 Z97 2-Way SLI UEFI DualBIOS ATX Motherboard

HDD : Seagate Desktop 2 TB Solid State Hybrid Drive SATA 6 GB with NCQ 64 MB Cache 3.5 Inch (possible additions here)

SSD : Samsung Electronics 840 EVO-Series 250GB 2.5-Inch SATA III Single Unit Version Internal Solid State Drive

RAM : Corsair Vengeance 8GB (1x8GB) DDR3 1600 MHz (PC3 12800) Desktop Memory

CASE : Cooler Master N400 - Mid Tower Computer Case with Fully Meshed Front Panel

HEAT SINK : Cooler Master Hyper 212 EVO

I appreciate whatever help I can get.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Thu Aug 07, 2014 7:50 pm 
Million Club 2+ [PC]*
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Are you getting one or two GPU's?

Also, you want to get a kit of ram. If you're happy with 8GB, buy a kit of two sticks of 4GB. It will then run in dual channel mode on that motherboard and improve memory performance.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Thu Aug 07, 2014 8:11 pm 
Smithfield
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Joined: Sun Jun 18, 2006 7:37 pm
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The breakdown:

  • 300W Minimum
  • 450W-500W recommended
  • 600W to be safe

That system will probably go up to 150W-180W off the wall for a nominal load, 250W at the worst if you're trying to deliberately tax it. Make sure to get a really good quality PSU though with 80PLUS Bronze or better.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Thu Aug 07, 2014 9:01 pm 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
Posts: 6
Thanks for the prompt replies.

First off Quakindude, I'm sticking with one GPU for now but I'm toying with the idea of Crossfire in the distant future. Also, I was of the impression that getting a single stick of 8GB was better than 2 of 4GB, plus it would allow me to get more memory into the machine over time. I've never really researched dual channel mode.

LatiosXT, I was looking at a Corsair CX500 initially but one of those PSU calculators quoted 650W so I was a bit wary of it. I do believe I'd stick with a Corsair though, but I've read that I shouldn't go with a PSU that has too high a wattage. Is this something for me to worry about?


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Thu Aug 07, 2014 9:14 pm 
Smithfield
Smithfield

Joined: Sun Jun 18, 2006 7:37 pm
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Most PSU recommendations over estimate due to the fact that not all PSUs are created equal. A lot of the cheaper stuff may technically output the rated wattage, but not at the operating conditions or lines that you want. Though there's no problem if you get a PSU with a lot more wattage than you really need.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 4:04 am 
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Kabal, check the link below. It states dual channel memory architecture. Using two sticks of RAM will give you a better memory throughput speed.

http://www.gigabyte.us/products/product-page.aspx?pid=4957#sp


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 7:05 am 
Thunderbird
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Kabal wrote:
.... I was of the impression that getting a single stick of 8GB was better than 2 of 4GB, plus it would allow me to get more memory into the machine over time. I've never really researched dual channel mode.

LatiosXT, I was looking at a Corsair CX500....

The difference in performance between single and dual channel mode is pretty small. If you plan is 8Gb now without having to chuck the sticks to max in the future then that makes sense to me. I did that myself on a fairly new system I built for that reason.

The CX500 is a good unit.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 11:14 am 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
Posts: 6
I've decided to go with a CX600 instead, it's $8 extra compared to the CX500 on Amazon. How does that sound? It's rated at 80 Plus Bronze and seems like a sweet-spot for the calculations I've seen.

In regards to dual channel, I've done a bit of reading and I think I have a rough understanding. It basically allows the DIMMs to help each other, if one is busy the other is available to pick up the slack. I've read that it grants advantages for some applications but it hardly shows improvements for gaming. My intention is not to stay with 8GB forever though. I do intend to source a second 8GB stick and I imagine then I'll have dual channel while still leaving room for great improvements in the future. What do you think about that?


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 11:33 am 
Smithfield
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Joined: Sun Jun 18, 2006 7:37 pm
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Dual channeling is kind of a tricky business, though I don't know how tricky it is. If you're going to add another stick, you stand a better chance of it being from the same model. Otherwise it may not work and I don't know what'll happen, maybe the computer whines if two different models are on the same dual-channel slots.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 2:22 pm 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
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Yeah, the second stick would be an identical module.

I just used NewEgg's PSU calculator and it's telling me I'll need 880W with the same components I listed in up top. =|


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 2:42 pm 
Smithfield
Smithfield

Joined: Sun Jun 18, 2006 7:37 pm
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I wanted to avoid the long exposition on power supply wattage estimations, but I guess it's time to do this.

If you're given a power supply estimation, it mostly comes from the fact that, as I said earlier, not all power supplies are created equal. Notoriously, for what must constitute a X Watt power supply, the power supply only needs to supply that much power in total across its 3.3V, 5V, and 12V rails at one of three different operating temperatures: 25C (lab testing), 40C (normal commercial operation), and 65C (industrial).

Anyway, a lot of cheaper brands will often shortchange the 12V rail, which is the where the bulk of power comes from (CPUs and GPUs operate purely form the 12V rail) and give the rating at the 25C operating temperature. Most power supplies, given a room temperature environment, really operate at close to 40C. And the hotter a PSU runs, the less power it can deliver. Thus when choosing a power supply, quality ones will have much of the power being delivered to the 12V rail. Some manufacturers, like Seasonic, actually report its power supplies providing less total power than if you added up what it says on the sticker (mine is a SSR-450RM, which if you looked at the sticker and added up the wattage, the unit makes over 550W, despite being sold as a 450W PSU).

Since Newegg and a lot of other vendors can't predict which power supply you have, they often grossly overestimate your power budget to account for this. I've been able to hone in my estimation figures by buying a Kill-A-Watt and noting power usage across every build I've done. Theoretical stuff be damned, I only care about real-word measurements!

I guess to make this easier, for a high end system using a video card with two 6-pin PCIe plugs, you must have at the minimum 30A coming from the 12V rail (360W). If using two eight pin, we'll say 40A. You can effectively disregard the other rails because they're not really used for much of anything.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 5:22 pm 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
Posts: 6
Wow, thank you for that actually. I'm about to go do some more reading into how a PSU works.

I've just seen my GPU's power requirement of 500W on Gigabyte's website. What should I make of that?


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 6:22 pm 
Smithfield
Smithfield

Joined: Sun Jun 18, 2006 7:37 pm
Posts: 5214
Your setup should be fine with 500W-600W. That's it. The more you look into this, the more answers you're going to get that conflict.


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 Post subject: Re: What PSU Wattage Should I Get?
PostPosted: Fri Aug 08, 2014 8:04 pm 
8086
8086

Joined: Thu Aug 07, 2014 6:02 pm
Posts: 6
Oh I've already decided on the CX600M (modular looks neater). I was just curious.


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