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HX series wattage and efficiency clarification


NickSt

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Hi there. I consider buying one of the HX PSU's, but there's one simple question to the ppl. who know. It says that, for example, 620HX has 620 watts of power and ~83% efficiency. So are these 620 watts of power the actual power the PSU draws from the wall, and applying the 83% we get around 514W output for the computer, or the 620 watts are the output power, and applying the efficiency percentage we get around 747W of power drained from the outlet?

 

 

P.S., and does somebody know why the power calculators found on the Net show such different results? I've been getting results varying from 500 to 680 watts required for my system... :confused: Don't know whom to believe cuz I can't calculate everything by hand.

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Efficiency rating is a measure of how well a supply converts AC power from the wall going into the supply to DC going out, so 100 watts going in with an 83% efficient supply equals 83 watts coming out (83% efficiency for a supply is very high rating by the way). The missing power is waste, usually in the form of heat. The 620watt rating is the maximum continuous DC output the supply has been designed to produce. Most PC's don't draw anywhere near that amount of power continuously. A PC like the one mentioned in your system specs probably sits at idle somewhere in the range of 180 to 250 watts. When you start doing something on it, the power supply draws only what it needs from the wall to keep up with demand. If your surfing the internet or writing a report say, demand goes up a little bit. If you fire up a 3D graphics intensive game, demand goes up a lot bit. There's also brief spikes in power usage that can go very high, so a supply should be able to meet those demands. When choosing a supply the best place to start is by looking at the minimum power supply recommendations of your videocard manufacturer. They'll usually list two numbers: a wattage size and how many amps a supply should be capable of producing on the +12volt rail. Those recomendations are usually based on a base line system: single hard drive, single cpu, two sticks of RAM, a PCI card, and a single optical drive. From your system specs, I'd say the HX520 would be more than adequate.

 

As to the power supply calculaters, a bit tricky, they're estimating how much power based on how hard the components are being pushed while using the PC, ala is everything in the PC being run at max 25% of the time, 50% of the time, 75% of the time, or 100% of the time. This would obviously have a big effect on the recommended size of the supply. The better calculators will have an option to select a percentage. When I use a calculator, what I'll usually do is see what number it comes up with for wattage at 50% then add 15-25% for headroom (supplies run cooler and last longer with headroom).

 

Hope this helps.

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A PC like the one mentioned in your system specs probably sits at load somewhere in the range of 180 to 250 watts.

Fixed. :nodding:

 

NickSt, your rig will consume the same amount of power from a 300W psu as it would from a 620W psu. The load on the wall outlet will depend on the overall efficiency of the unit. Overall a Corsair VX450 would provide more than enough power for your rig.

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OK guys, thanks for the answers first of all.

 

Let me make a small clarification why I'm changing my supply, because right now my 400W is enough for the system. I'm doing some overclocking and I also plan on expanding my system. When I overclocked my CPU last time from 3.2 to 3.7 the PC started to restart at load (duh, that die consumed ~150W at that time! Yes, I tried going down with the OC, it's just too much for the supply), so I think it's more that obvious that I need more power for that. And, the videocard is in the queue for a voltmod after that (another ~150-170W). I updated my system specs mentioning what the new supply WILL have to power, so that it's more clear what and why do I need.

 

Garvin and Wired, thanks, but I knew those calculations. The only thing I was actually asking was about the labeling of the HX's. I mean, I wanted to find out whether the 620/520 watts are input or output, but as I understand thats the output of the supply, so applying the efficiency I get what it draws from the wall.

I didn't ask that because of my AC bill, but because when I was choosing a wattage I was planning for ~500W consumption by the PC, then I applied 83% and got that I needed something around a 600W PSU. But again, it seems that those numbers on the label are the actual output power, so I'd go with an HX520, 620 would be an overkill. But now I start thinking that if I get a 520 it will run much closer to its limit, hence hotter and will live less. What do you think?

 

As to the power calculators... Well, the rig doesn't run at about 50% when you're gaming, you'd better choose 100% and add the 15% headroom after that, IMO.

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At full load, I don't see your listed system EVER going over 300w - 325w max.

You mean the system with the stuff in brackets as well? How's that possible if the CPU alone draws ~160-180W (at full load, or always, not important), add the video for another 140W, that's already 300W.

 

Btw, using this and this calculator gives that devastating difference in needed wattage.

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You can try using our PSU Finder.

Yeah, but that's such a simple calculator. I used it before. And once again about my concern stated above, the calculator says HX520 would be OK for me, but it may run at near maximum "capacity", and as I understand that's not good and I should leave plenty of headroom.(?)

 

 

because our 450w would be enough for your system, does not mean that everyones 450w would be sufficient.

Ppl, why do you keep telling me that 450W would be OK for me if I tell you that I have a 400W supply right now, which is not enough, and I have around 150W more to accomodate somewhere!

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Ppl, why do you keep telling me that 450W would be OK for me if I tell you that I have a 400W supply right now, which is not enough, and I have around 150W more to accomodate somewhere!

Because it is more than enough. Our 450 is capable of running ANY single video card made, OCed or not and also in tandem with an OCed quad core CPU. I don't think it is possible for an E6400 to draw more than about 145w MAX under any conceivable circumstances.

 

You need to look at what your system is going to potentially pull from the 12 rail.

 

A HD pulls about .5a or 6w MAX from the 12v rail when it's actively reading and writing. If you have all 4 HDs wide open, 24w.

 

Optical drives might pull a full 1.5a when burning a disk, so 12-18w. So, 36w for your optical drives if you were burning a disk on both.

 

Your CPU MIGHT pull 145w under Orthos Prime both cores at 100% on large FFTs.

 

If your video card is wide open you say with the volt mod, 140w.

 

Added up, this is 345w on the 12 rail which is 28.75a. The VX-450 is rated at 396w/33a on the 12v rail which is cutting it close but, it will do your system with ease. However, you have to consider that you'd need to be running a CPU max benchmark, running a video benchmark and/or video game, doing multiple file transfers to and from from all 4 HDs, burning 2 disks in the optical drives, etc etc etc to EVER pull this much power through your system. It's not going to happen. Under any realistic load you can get your system to run, it will max out at about 300-325w total power consumption.

 

Personally, I would run the VX-550 or HX-520 on that system but, the VX-450 WILL do it easily.

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Because it is more than enough. Our 450 is capable of running ANY single video card made, OCed or not and also in tandem with an OCed quad core CPU. I don't think it is possible for an E6400 to draw more than about 145w MAX under any conceivable circumstances.

 

You need to look at what your system is going to potentially pull from the 12 rail.

 

A HD pulls about .5a or 6w MAX from the 12v rail when it's actively reading and writing. If you have all 4 HDs wide open, 24w.

 

Optical drives might pull a full 1.5a when burning a disk, so 12-18w. So, 36w for your optical drives if you were burning a disk on both.

 

Your CPU MIGHT pull 145w under Orthos Prime both cores at 100% on large FFTs.

 

If your video card is wide open you say with the volt mod, 140w.

 

Added up, this is 345w on the 12 rail which is 28.75a. The VX-450 is rated at 396w/33a on the 12v rail which is cutting it close but, it will do your system with ease. However, you have to consider that you'd need to be running a CPU max benchmark, running a video benchmark and/or video game, doing multiple file transfers to and from from all 4 HDs, burning 2 disks in the optical drives, etc etc etc to EVER pull this much power through your system. It's not going to happen. Under any realistic load you can get your system to run, it will max out at about 300-325w total power consumption.

 

Personally, I would run the VX-550 or HX-520 on that system but, the VX-450 WILL do it easily.

 

Hm, well, that's convincing enough). Yeah, I am actually testing my CPU with Prime95 Large FFT 2 copies for each core for some 10 hours, and the video with that hairy cube from ATI tools (or what was the name), but you're right that I won't have the HDD's wide open, 2 DVD's burning and 2 stability tests at the same time.

The only thing I am concerned are the bunch of PCI-E cards I'm gonna stick in like a sound card and a TV-tuner, also I have a HDD and some other devices powered from the USB ports and the future GeForce 9 series, I hope I'll be still capable to overclock and run smoothly a high-end card with a 520 W. I think I'll go with that one for the modularity, otherwise the VX's are a great choice...

But still I don't understand why some power calcs give me 600W. Anyway.

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Many of the power calculators are simply pretty Excel sheets. And, we have no way of knowing if the info the developer put in was correct. And, are they calculating all of it at 100% load?

 

The HX-520 is a good choice and has enough reserve power for most anything you'll see in the near future. Even the dual GPU video cards are probably not going to pull more than 200w-225w. The system in this review pulls about 410 total with new ATI 3870 GX2 card: http://www.hardwarecanucks.com/forum/hardware-canucks-reviews/4236-ati-radeon-hd3870-x2-1gb-review-14.html

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  • 2 weeks later...
OK, I have another question, or rather request. Could I get detailed specs of the both HX series models? I just received an 8-page detailed spec. of an FSP power sourse, so I guess I could get such from Corsair. I'd like a copy, if possible, please (will send my e-mail address to someone, if possible to get the specs).
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For example section 3.1 specifies among other things the maximum loads among all the different combinations of rails, and for certain combinations (like +3.3 and +5) several maximum loads are specified depending on the Ampers consumed on each rail (like iff one rail is 22A then the other 11.4A max. load, and then iff 6A then 22A max. load, etc.) Again, this is just to show you what I'm talking about.

I hope I was clear enough (?)

 

would largely be proprietary info.

It would be for personal use anyway :-D

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All of the Specification information is posted on our web site in the Power Supply Seection, just click on the model in question and you will see the detailed spec.

Ram Guy, of course I know that page, I've read it numbers and numbers of times, and since I am writing here requesting additional information I can't find what I'm looking for on the web page, don't you think? Or your answer is a kinda 'official company response' implying that we ain't give you any more than what's on the web page?

I'm sorry I have to be a little sharp in my language, but I don't really love such answers.

 

For example(that is, the important part of my post is the previous one, not this one), for HX520, is it possible to simultaniously continiously load +3.3V and +5V to their maximum of 24A? And what is the total combined wattage of +3.3V, +5V and +12V? Is it 520W, or less, If I load everything? If I add the numbers from the "maximum combined wattage" fields I get a really high number.

 

And how about such data as insulation resistance, or output and power_good signal risetime? Just look at the contents table I posted previously; I didn't spend my time typing it in manually for it to be ignored.

Thanks.

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Nothing as in "no reply" or "not providing the information"? In any event you may want to contact Seasonic & Channel Well Technology directly to see if they will provide you with the documents.

 

Give it a little more time, what time did you send the email?

 

We do not make public our internal specifications. All the specs that we will release are in the manual or on the box.

Thanks.

sakurs :(::D:

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