How big of a psu for this build?

Hello all,

I was wanting some input for a redommended psu size. As for the psu itself I'm going with the evga supernova... Just not sure how much juice I'll need.

Asrock fatality z97x killer mobo (Ive read it's a bit power hungry?)
I5 4690k
7 case fans (3 x 140, 4 x 120)
Intel 530 ssd 120gb
WD Black 7200 rpm 1TB
Corsair Vengeance 1600mhz 16GB (2x8)
Asus Strix 970

The system will be running at stock speeds.

How do you figure out the max wattage your system will use? I know the GPU says recommended is 500 but I'm always afraid I'll go to low. At the same time I don't want to waste money on extra wattage I don't need.

Thank you all.

A quality 550W PSU will power that rig and not break a sweat... even with overclocking both the CPU and GPU under ambient temps.

http://www.newegg.com/Product/Produ...51119&cm_re=Seasonic_G-_-17-151-119-_-Product

There are PSU calculators out there that do it for you..

But the CPU is 84W, GPU's TDP is 150W, the mobo/ram/fans wont take close to 100W (50W really). SSD is a couple of watts, HDD is several W.

You could overclock to the limits of a custom CPU+GPU water loop on that G-550 and still have extra headroom.

Good info thus far, but let me add this:

Some of us prefer to run a PSU at 50% load, because it's generally more efficient than at, say, 75%.

If, with that GPU, plus overclock, you find the load would be around 350 to 400 watts, I personally would aim at the 700 to 750 range if there are bargains, with 650's if deals are best there.

The good 550's will provide 550 for 8 hours a day for the duration of the warranty. The great ones will provide 550 24/7 for the duration of the warranty. The greater the headroom, the longer we'd expect the PSU to last, and the more efficient it should operate.

jasonlylevene said:

Good info thus far, but let me add this:

Some of us prefer to run a PSU at 50% load, because it's generally more efficient than at, say, 75%.

If, with that GPU, plus overclock, you find the load would be around 350 to 400 watts, I personally would aim at the 700 to 750 range if there are bargains, with 650's if deals are best there.

The good 550's will provide 550 for 8 hours a day for the duration of the warranty. The great ones will provide 550 24/7 for the duration of the warranty. The greater the headroom, the longer we'd expect the PSU to last, and the more efficient it should operate.

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The power supply that both EarthDog and I would suggest for this build (the Seasonic G-550) is efficient to within 1% of its maximum at the loads the OP will see.
Also, it's one of the best built 550W units on the market, I daresay it would last 5+ years at 24/7 operation at its max wattage.

The efficiency argument, to me, just isn't one is most cases. The difference in efficiency between most PSU's between 50% and 75% is 1%. You will NEVER make up the cost between a 550W PSU like I selected (very high quality or 'great') versus say another 750W high quality (or 'great') PSU, like the EVGA Supernova G2 unless you F@H/mining/other distributed platforms (im suggesting 24/7/365ish operation here).

As far as the power that system will use, check out my review on a already highly overclock GTX 970 (Galax HOF). You will notice there I hit 320W AT THE WALL with further overclocking than out of the box. Assuming 90% efficiency (platinum PSU), that is actual use of around 285W. Unless you are bios modding that 970, you won't be using more than 190W out of that card. When I was running 4.9GHz on the CPU and pushing that card to the limit, I peaked at around 420W AT THE WALL. Again, 90% efficiency, that puts us around 380W actual use. I should also add the review system has 2 HDD's, 5 fans, 3 SSD, and a water pump too.

Why spend $35 more? The ONLY reason to, what I am going to call overbuy, is if there is a possibility that you will go multiple GPUs in the future. That G550 will last through its warranty at its rated wattage... there would be no appreciable difference between running it at 50% load or 75% load (which it wouldn't be regardless).

I certainly wouldn't argue against the Seasonic G-550 (for some reason I thought the link was to an EVGA 550, a CTW or FSP OEM). I would expect a Seasonic to manage the rated power 24/7 for the duration of the warranty.

In any case, the point I make about efficiency was primarily a suggestion, not a strong diversion from the 550 or certainly not from Seasonic.

However, efficiency and heat go together, and heat and deterioration do too. If you look at some of the reviews, for example, you'll notice support for your point...the difference in efficiency on the 550 from 300 watts to about 450 watts is, as you pointed out, only about 1%.

The heat from exhaust goes up about 4C in that range. This is really what I'm getting at. I tend to assume this kind of thing is obvious, but I realize it's not. A 1% change in efficiency isn't going to change one's power bill by a useful amount, but a 4C increase in the heat from the exhaust indicates how much harder the unit is working.

If I run a machine 24/7 (I know, the OP didn't say), I tend to consider how that power supply will perform in 4 or 5 years. For some office machine running 8 to 10 hours, I don't bother.

I consider that point because I frequently end up with a "retired" machine that's 3 or 4 years old, and a PSU that might be applicable to other builds if, when I bought it, I chose something I knew wasn't going to be used up in 4 years. If I do elect to use an older PSU, I want to know it would be useful for at least another 2 close to it's operating spec. One of the ways that does NOT happen is if the unit was used at or above 75% of it's power rating, where everything was hotter all day/night, and .... here's the part that matters most to me ... after unobserved lint has clogged heatsinks, fans and openings.

I agree it's not a reason to spend $35 on a build where the budget matters.

For an old engineer that insists the PSU is the last thing that will ever give me a problem, I have certain margins I keep in mind which ensure that.

The best builders, Seasonic among them, choose to label a unit at, say 550w, when the design itself, if reverse engineered, would actually qualify to be a fairly good 650. So, it's likely the G-550 is already beefed up to account for the point I'm making.

That said, there are some Superflower builds which are similar efficiency, at 750W, at the same price as this 550, which survive their hotbox tests with superb results. The surprising CAPSTONE 750, for example...I would never have thought I'd suggest a Rosewill PSU to anyone, ever...but it's a Superflower which reviews show to be a very good alternative option at the same price point.

Don't take that as suggestion to consider over the Seasonic. The one thing about Seasonic is...they're one of the very few that actually make power supplies. That's a big deal!

TL;but read!!!!

For an old engineer that insists the PSU is the last thing that will ever give me a problem, I have certain margins I keep in mind which ensure that.

Click to expand...

The G550 already has that headroom. IMNSHO, that overhead is too much. If I told you what I ran on what PSUs, with your thinking, your head would pop off your shoulders (one example, I run a 295x2 and overclocked 4930K on 750 Supernova G2... LOL..)

Nobody thought Rosewill would make something decent. But 'dat sun... 'dat dogs rear end.

I wouldn't spend the $35 where budget is not an issue (wow, lots of negatives there!). I work for quasi government too. They look at me funny when I'm under budget and get it done with quality materials..

jasonlylevene said:

I certainly wouldn't argue against the Seasonic G-550 (for some reason I thought the link was to an EVGA 550, a CTW or FSP OEM). I would expect a Seasonic to manage the rated power 24/7 for the duration of the warranty.

In any case, the point I make about efficiency was primarily a suggestion, not a strong diversion from the 550 or certainly not from Seasonic.

However, efficiency and heat go together, and heat and deterioration do too. If you look at some of the reviews, for example, you'll notice support for your point...the difference in efficiency on the 550 from 300 watts to about 450 watts is, as you pointed out, only about 1%.

The heat from exhaust goes up about 4C in that range. This is really what I'm getting at. I tend to assume this kind of thing is obvious, but I realize it's not. A 1% change in efficiency isn't going to change one's power bill by a useful amount, but a 4C increase in the heat from the exhaust indicates how much harder the unit is working.

If I run a machine 24/7 (I know, the OP didn't say), I tend to consider how that power supply will perform in 4 or 5 years. For some office machine running 8 to 10 hours, I don't bother.

I consider that point because I frequently end up with a "retired" machine that's 3 or 4 years old, and a PSU that might be applicable to other builds if, when I bought it, I chose something I knew wasn't going to be used up in 4 years. If I do elect to use an older PSU, I want to know it would be useful for at least another 2 close to it's operating spec. One of the ways that does NOT happen is if the unit was used at or above 75% of it's power rating, where everything was hotter all day/night, and .... here's the part that matters most to me ... after unobserved lint has clogged heatsinks, fans and openings.

I agree it's not a reason to spend $35 on a build where the budget matters.

For an old engineer that insists the PSU is the last thing that will ever give me a problem, I have certain margins I keep in mind which ensure that.

The best builders, Seasonic among them, choose to label a unit at, say 550w, when the design itself, if reverse engineered, would actually qualify to be a fairly good 650. So, it's likely the G-550 is already beefed up to account for the point I'm making.

That said, there are some Superflower builds which are similar efficiency, at 750W, at the same price as this 550, which survive their hotbox tests with superb results. The surprising CAPSTONE 750, for example...I would never have thought I'd suggest a Rosewill PSU to anyone, ever...but it's a Superflower which reviews show to be a very good alternative option at the same price point.

Don't take that as suggestion to consider over the Seasonic. The one thing about Seasonic is...they're one of the very few that actually make power supplies. That's a big deal!

Click to expand...

So, answer me this, if the power supply is running within spec, what does it matter if the exhaust temp is 4°C higher?
Also not seeing your point about 750 vs 550, when this system is around 50-60% load on the 550W unit.

For Earthdog...you're pointing out $35 increase, but the CAPSTONE (they spell it all caps, I'm not yelling)..it's $7 less than the Season 550, and has 2 years longer warranty.

See? I'm not electing to spend more money. I'm electing more headroom, longer warranty. They're both 80+ gold.

Now, to ATMINSIDE and Earthdog, and OP if still interested:

It's heat, indicating stress.

Capacitors are consumed as they're used. They're like short term rechargeable batteries, only they charge in a tiny fraction of a second (sometimes a millionth of a second), and discharge over a second or two (or, at low loads, several seconds...like that LED that doesn't turn off for 15 seconds when you cut power).

In 4 years, most capacitors of the types used in power supplies, are consumed to about 50% of the rated values. they get warm, but the heat measured isn't coming from them primarily, that's coming from the semiconductors & their heatsinks, but it's a measure that they're pushing more current through the caps.

4C increase in the EXHAUST air (that is a raised voice, sorry)...that means the heatsinks are pushing out A LOT more heat. That's not like 4C on the core of the CPU. Think how much heat it would take for you to measure a 4C increase in the air coming off your HSF.

At that point where caps are 50% consumed, the electronic noise of the PSU starts to increase, which makes the motherboard's own caps and VRM's work harder to keep things moving. That may still be in overall spec, but the point is...wear.

If the addiitonal headroom offered another 2 years of operation, and cost $7 less...as in the CAPSTONE....why would you argue against that?

Headroom isn't about having unused power, or about waste.

It's about robust behavior against usage over long periods of time.

BTW, just so the OP understands....this is more of a debate on the philosophy of these choices, not an argument about what should be recommended to you. These two are curious as to why I think a PSU should be run at 50%, and think to themselves it's overkill...and they thought it was additional cost.

It's actually $7 less. There are several points I'm making, some without outright stating.....

1) On Power circuits, overhead is longevity...it's not waste, usually. That's an engineering principle long held (I'm an electronics student from decades ago).

2) While Seasonic is the maker of their units, most other brands are OEM vendors. Corsair is an example. Someone else makes the PSU's, and if you dig into who THAT really is, you might find surprises, like the CAPSTONE.

3) It's not just what the components do today. It's what they do in a 3 or 4 years, when lint, wear and the effects of usage take their toll.

4) The ratio of the OP's build looks more like 61% than 50% to me - but if the G-550 is really a 650 (as everyone else would probably lable it), then it IS more like 50%.

Now, let me say again, the Seasonic is a great choice. I'm not contradicting Earthdog and ATMINSIDE. I'm pointing out some thinking from years of engineering, consulting, usage. After you do something for a few decades, you tend to learn things. We've had a debate here (it might continue), on a means of thinking about this choice.

I apologize if that's become a thread hijack. Some don't like that, others enjoy seeing how a selection is determined.

Public debate, as it is in science, is only a good thing (sometimes it's really great).

The capstone... sorry... CAPSTONE (lol) being $7 less is also a solid choice. The PSU didn't review as well as the G series does, but its still a good PSU versus the G series that are 'great'. I think my hoity toity pinky is up in the air on the Seasonic and other 'great' maker units.

I hear you.. and appreciate the 'philosophical' discussion about how we came to that decision. Many other members it could degrade into an argument...

"I think my hoity toity pinky is up in the air on the Seasonic and other 'great' maker units. "

Well, Seasonic is one of the legends that deserves loyalty.

It's almost embarrasing to suggest one look at a Rosewill....I mean, it's like "house brand" to the ears. I have one of those CAPSTONES (not yelling ), they're good stuff. It's not the BMW of PSU's, but it's worth the price charged and the Japanese caps inside will last.

BTW, for OP, caps are usually the first thing to go on a PSU that still runs.

Oh, also for OP, the Seasonic is way superior to the EVGA. That's why they didn't even give the EVGA a second thought.

Several weeks back, I got a great for a Seasonic 620w M12II for around $54.99 sale price. The price was so good it was my 2nd PSU purchase after recently buying a 520w S12II around regular price. Unlike my PSU, my original plan to buy the lowest wattage PSU (a 330w Seasonic) for my needs backfired, and while it still lasts me and serves a backup or a future HTPC build, I was only using 60-70% of the overclock potential of my GPU. It was underclocked at 650mhz and the OC goes all the way to 1100mhz stable, which resulted in nearly a 10-15fps increase. I don't OC my CPU, since I have a weak stock heatsink, but I did recently buy a Zalman FX-70 to cover most of my cooling needs with a fan as an acute supplement rather than as an obtuse complementary function. I also use a Prolima-tech Samuel 17 heatsink, which is very capable up to 95w and has a thicker base plate (the part that makes contact with the CPU) than the FX-70 (which takes up more space but disperses heat a little more evenly; still, it could use a thicker base plate). Noctua coolers also look very decent.

Sorry to be off-topic about that, but I agree with the 50% usage planning for on a daily basis. My 520w system averages around 220 watt, which is close to 50% and is less stress than I would ever want to use on a regular basis. I use another, more efficient mini-ITX PC for more every-day use. It uses only around 100w with an AMD APU. I figure it's good to build budget PCs that don't use a lot of watts for the majority of use and have a gaming PC for the occasional intensive stress on the PSU. Since I game so infrequently (or do for short-intensive periods of less than a month to complete a game), I figured a 620w PSU will suffice even for a new SLI/CFX build. I'm planning something similar to yours- 95w CPU +2 190w peak GPUs. Adding mobo, fans and SSDs, should put it under the 576w rated limit on the 620w and represent around an 88% usage of the PSU. If I gamed everyday, that would not be sustainable. I would definitely purchase a 750w or greater instead, but for now, the quality of the PSU plus the infrequency of stressing the PSU to that peak active load should make 620w enough for that type system. The sale price led me to save $20-$30 of the regular price and it adjusted my plans slightly without feeling limited where I can't game on dual GFX when I want. I thinkthe PSU would endure it if I used the system 3-4 months a year, 8 hrs a day without much less of a loss its typical lifespan, since both GPUS don't turn on unless gaming;I'm not sure about video playing since I don't see why it'd need two GPUs to play 4k video, etc. Encoding is a different animal.

I ended up ordering the Supernova 750 G2... The stellar reviews and extra headroom you can't go wrong.