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Trying to decide on a Corsair PSU. What wattage and series should I choose?

fireaza

24 months ago

I'm trying to decide on a PSU for my new build. I guess the first place to start is how many watts it should be! The system build is saying that my proposed build will draw 583W (I have a crap-load of HDDs!) and from what I've read, you should use a PSU that will be at around 50% of it's capacity for best efficiency. For my system, that's going to be 1000W.

But then I was thinking maybe I should choose a 850W PSU instead. I probably do more internet browsing than gaming on my PC, so it would probably be best to assume that most of the time, the system won't be under load. So, choosing an 850W PSU should keep my watts close to 50% for the largest percent of the time that I'm using it and would be the most efficient, right? Would this be a good idea?

The next is models. I'm kinda limited on what brands are sold here in Japan, it seems like Corsair is probably the best brand that available to me. Looking at the recommend PSUs on Tom's Hardware, there is some pretty good showing of Corsair PSUs. They appear in the "best 1000" and "best 1500W" categories and usually have almost nothing listen in "cons".

Something I'm curious about is how identical a PSU series is between different wattage models. For example, Tom's calls the AX1500I "the best PSU money can buy" and Corsair's website says the AX series are their flagship series. So you would think that the AX series is incredible and would appear multiple times in Tom's "best PSUs", right? But they only appear once! In fact, the HX series make more appearances, not to mention they're more recently reviewed than the AX series. Why is this? Surely all PSUs in a series are exactly the same but just at a different watt rating? I have heard for example that the HXi series aren't as good as the older non-i series, but these are at least two different series, despite the similar name.

TL;DR should I go for a 850W or 1000W PSU? Should I choose the AX or HX series?

Comments

  • 24 months ago
  • 2 points

from what I've read, you should use a PSU that will be at around 50% of it's capacity for best efficiency.

And why do you think you should try your hardest to stay at best efficiency? Why is efficiency so important that you'd buy a twice as powerful PSU just to get the highest efficiency under load?

I'm kinda limited on what brands are sold here in Japan, it seems like Corsair is probably the best brand that available to me.

What does "best brand" mean? If a brand is perceived as best or better than another, does it mean every single one of their power supplies is better than all PSUs from all other brands? Or does it mean their top-end unit is better than other brands' top-end units? Or does it mean it's just most popular with the people, or even something else?

Do people buy graphics cards by brands? If they can choose between Gigabyte GTX960, ASUS RX580, and MSI GTX1080Ti, do they choose by "best brand" or by performance of particular models?

Surely all PSUs in a series are exactly the same but just at a different watt rating?

No, it's almost never that way in PSUs. It's not effective to make a single design that spans from 550W to 1200W or similar values. You need a beefy design to handle 1200W, but why would you also use it in an only 550W unit? You use a smaller, cheaper design in it.

I have heard for example that the HXi series aren't as good as the older non-i series

Total lie.

You've told us many of your thoughts about choosing power supplies, but we can't help with picking a PSU for your build... if we don't know your build.

  • 24 months ago
  • 1 point

Oh right, I should probably post a link to my parts list! My bad! pcpartpicker

And why do you think you should try your hardest to stay at best efficiency? Why is efficiency so important that you'd buy a twice as powerful PSU just to get the highest efficiency under load?

I'm concerned about efficiency because I know this PC will be power-hungry, but I want it to use as little electricity as it can. Plus, it would be nice if the PSU's fan doesn't need to spin up either.

What does "best brand" mean? If a brand is perceived as best or better than another, does it mean every single one of their power supplies is better than all PSUs from all other brands? Or does it mean their top-end unit is better than other brands' top-end units? Or does it mean it's just most popular with the people, or even something else?

I'm looking for a good starting position. The range of PSUs are quite limited here in Japan, so I thought I'd start with whichever brand is available here who have a reputation for good PSUs (like Antec was back in the day).

No, it's almost never that way in PSUs. It's not effective to make a single design that spans from 550W to 1200W or similar values. You need a beefy design to handle 1200W, but why would you also use it in an only 550W unit? You use a smaller, cheaper design in it.

Oh, well there you are then!

Having looked around some, it seems like Seasonic's Prime Titanium series are considered some of the best PSUs around (jonnyguru gave them near perfect scores) and it seems they've had a limited release in Japan. I was able to find stock of the 750W and I would totally choose this one, but there's still the issue of the efficiency curve. Now, obviously a 750W PSU can power a 583W system. But that's well below the +50% figure I see being passed around online. Thoughts?

  • 24 months ago
  • 3 points

I'm concerned about efficiency because I know this PC will be power-hungry, but I want it to use as little electricity as it can.

You shouldn't worry about that: the difference you pay for a twice as powerful PSU is several times bigger than the difference you'd pay for electricity.

Plus, it would be nice if the PSU's fan doesn't need to spin up either.

If you want a quiet PSU, you buy a quiet PSU (with a relaxed fan profile and quiet fan) - not just "blindly" get an oversized PSU.

I'm looking for a good starting position. The range of PSUs are quite limited here in Japan, so I thought I'd start with whichever brand is available here who have a reputation for good PSUs (like Antec was back in the day).

Would you paste some links to online stores, so we can see the full offer and prices?

The most important thing to mention is that a whole normal PC with i7-8700k and GTX1080Ti will only draw 350-400W when overclocked, so that 583W figure is grossly overestimated. However you have a ton of HDDs, which may take power not only from +12V, but also from +5V. According to WD and Seagate specifications, a WD40EZRZ consumes 21W "peak" (probably at startup) and 5.3W under load, while ST4000DM000 takes 7.5W under load and an unknown amount at startup. And they don't specify exactly how much power they take from +5V. But assuming those drives aren't going to suddenly spin up all at once while you're under heavy load, that's not a problem.

  • 24 months ago
  • 1 point

You shouldn't worry about that: the difference you pay for a twice as powerful PSU is several times bigger than the difference you'd pay for electricity.

I see. Does this also apply to the mythical "efficiency curve"? If the PSU is running at say, 70% is this really that much of a difference from the supposed ideal 50%?

Would you paste some links to online stores, so we can see the full offer and prices?

Best places are going to be Amazon.jp and Tsukumo. For example, here's the Corsair HX850 on Amazon.jp: http://amzn.asia/6QkJaOH

And here's the Seasonic Prime 650 on Tsukumo: https://shop.tsukumo.co.jp/goods/4942322000909/202810000000000

The most important thing to mention is that a whole normal PC with i7-8700k and GTX1080Ti will only draw 350-400W when overclocked, so that 583W figure is grossly overestimated. However you have a ton of HDDs, which may take power not only from +12V, but also from +5V. According to WD and Seagate specifications, a WD40EZRZ consumes 21W "peak" (probably at startup) and 5.3W under load, while ST4000DM000 takes 7.5W under load and an unknown amount at startup. And they don't specify exactly how much power they take from +5V. But assuming those drives aren't going to suddenly spin up all at once while you're under heavy load, that's not a problem.

Ah, that's very true! All my HDDs are indeed the cause of a lot of this system's power draw, but there's only going to be around 3 or so (I'll be using 3 HDD pools with around 3x HDDs in each pool) actually spinning at a time thanks to Window's ability to put non-active drives to sleep.

  • 24 months ago
  • 2 points

Does this also apply to the mythical "efficiency curve"? If the PSU is running at say, 70% is this really that much of a difference from the supposed ideal 50%?

See here: https://i.imgur.com/3BRel35.png 100% load is 87.9%, half load is 91%. I don't know why people think it's important. It's equivalent to suggesting "disable Windows taskbar transparency to get 0.01FPS more in games", except in this case you pay $50 more for a larger PSU, to save $2.50 a year from 2% higher efficiency.

Try to find Corsair TX650M, BitFenix Whisper M 650W, Seasonic Focus Plus Gold 650W, Corsair RM650x, or Corsair HX650 Platinum. The first two have 7 year warranty, and the others have 10 years. You can also take Seasonic Prime Gold/Platinum/Titanium 650W with 12 year warranty, but that's the only advantage you would notice.

  • 24 months ago
  • 1 point

Hmmm, it seems like the PSU in the graph you linked to is at it's most efficient when it's slightly under 50% load, rather than the supposed ideal of 50% and slightly above. But yeah, it's not a huge difference. I'll check and see how many watts my current gaming rig uses. The new build should be similar, though slightly less due to a newer CPU.

  • 24 months ago
  • 0 points

If PCPP says it’s drawing 583, then it’s not true. All wattage calculators are inaccurate.

That system will likely only draw 350 watts under normal loads.

If you want to learn more about PSUs (which I highly advise) then go to my profile. It should help you.

  • 24 months ago
  • 1 point

If PCPP says it’s drawing 583, then it’s not true. All wattage calculators are inaccurate.

Hmmm, are they at least a ball park estimate? I've tried other calculators and got a similar figure. There's obviously going to be a bit of inaccuracy though, since not all parts will be running at full-load and the calculator is based on the maximum load.

That system will likely only draw 350 watts under normal loads.

I saw a bunch of power consumption videos on YouTube, and around 350W seemed to be the average for a gaming PC. The only thing that makes this build unusual is the large amount of HDDs, but surely they alone wouldn't bump up the watts by 200W!

[comment deleted]
  • 24 months ago
  • 1 point

The 1080ti only reaches 250 watts if you torture test it. (aida64). Under gaming loads, it’s closer to 200 watts. The I7 would only draw around 60 watts under gaming load

(TDP isn’t the CPUs power consumption. It’s basically its heat output translated to watts)

So, around 250-275 watts for the CPU and GPU alone. Add some HDDs, fans, and the motherboard, you get around 350-400 watts under gaming loads. This is the most realistic as not everything in your system is at 100% load (which is what AIDA64 does)

Now, if you overclock the 8700k, then the power draw gets around 100-110 watts.

[comment deleted]
  • 24 months ago
  • 1 point

Okay, I've checked my current PC with a meter to see how many watts it consumes to give me a more accurate idea of how many watts this new build might consume. First, was a dual prime95 and furmark stress test. This got me a maximum of 420W (lols in pre-teen) but I thought I'd check a Uniengine benchmark for something a bit closer to what the PC will actually be doing (i.e running games). Strangely, this actually used more watts, around 444W average with a high of 448W. That is slightly above the supposed ideal 50% load, but I figure that since I'm moving to a newer, more power-efficient CPU, the new build should be a bit less than this. Plus, benchmarking isn't really a normal situation for this PC, not to mention it only uses around 200W when just browsing the internet, which is probably what it will be doing the most.

I think based on these figures, the unavailability of the 850W Seasonic Prime Titanium, as well as the seemingly better reliability of the 750W model (I've read a few stories of people having to RMA the 850W model multiple times) I think I'll go with the Seasonic Prime Titanium 750W for this build. Thanks for your advice guys!

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