How do I determine how much wattage I need in a PSU

By jnelsoninjax
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Grand Master

jnelsoninjax

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I would like to upgrade my PSU, I currently have a 700 Watt OCZ MOD Xtreme to power an AMD Phenom II X4 955, 8 GB's RAM, 4 7200 RPM HDD's, 1 optical drive and an Nvidia Geforce GTX 260. When I built this system 4 years ago, I ran into the issue with the PSU not having enough power on the 12V rail to power the GPU constantly, so I installed an Aux PSU just for the GPU, but it has a very bright and annoying blue light on the front panel and it takes up so much space inside the case, I wish to be rid of it. So how do I figure out how much power I need? TIA

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Grand Master

tsupersonic

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There are PSU calculators, such as this. I did a rough power calculation for your system using that link, and I got 391 watts. You can add in more details, such as fans, OC, etc.

I have the same exact PSU, and I'm powering an Intel Core i7 860, 16 GB of RAM, 2xSSD's, 2xHDD's, 1 optical drive and a GTX 560 Ti. Granted, the SSD's use less power than HDD's...

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Big b0b

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Depends on how much you spend.

If you spent 70$ on that 700 watt power supply it's not surprising it's having difficulty keeping up.

I myself have a 750watt power supply that ws over 150$. When it comes to power supplies, the more you spend, usually the better they are.

I run a phenom 2.4ghz quad core, 4gigs DDr2, 2 8800GTX's in SLI and 2hdd's + an optical and 4 fans without issue. I was running 4 hard drives, but that was a while ago and since switched to a single 1tb hdd.

A true 700watt power supply should be enough to run almost any system that isn't running a true Tri-SLI or Tri-GPU gaming rig.

Edit, this isn't the exact power supply I bought, it was almost 5 years ago when I built my PC, but it's the same brand. I'd buy from them again.

720watt

Damn thing weighs almost 6lbs. That's always a good sign when a power supply is hefty.

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Grand Master

Mindovermaster Moderator

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I would much prefer a Corsair, but that's me. Wattage isn't everything. You have to look at the amperage, too. Especially on the 12V rail. If it does not have enough amperage for your video card, you are going to have instability problems.

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Grand Master

Astra.Xtreme

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It looks to me like he has 46 Amps available on the 12V rails, which I would think is plenty for his PC.

Are you daisy chaining any of the molex plugs together? If so, it's generally not a good idea to do that except for fans.

mxsp_wattage_charts.jpg

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CG-88

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That website is reasonably good, just hasnt been updated for 660ti's.

I used to try and determine max load power amounts that are generally listed on manufacturers websites and figure it out that way.

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Grand Master

Mando

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I would much prefer a Corsair, but that's me. Wattage isn't everything. You have to look at the amperage, too. Especially on the 12V rail. If it does not have enough amperage for your video card, you are going to have instability problems.

Precisely, wattage alone aint the most important, its the ampage along those rails, the higher the better (and seperate 12v rails) is more important.

I run a Corsair Modular 650W PSU (high am ratings & 3 12v rails) and the following without issue.

Core i7 2600k @4.8ghz OC mode

Asus Z68 Mobo

2x 4Gb DDR3 2133Mhz Mushkin Ram

Nvidia 570GTX (Superclocked)

2x Vertex 3 60Gb SSDs

2x320Gb Sata II Raid drive

Sata II Optical

6 Hub powered USB devices

4 X PWM Case Fans

1x120mm PWM Case Fan

Zalman 120mm CPU cooler.

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