How close am I to my max ?

[Gryz]

I might buy a gtx980Ti.
Reference gtx980Ti's are using maximum 250W.
Factory-overclocked after-market gtx980Ti's are using around 275W.
I guess if you overclock yourself, and increase TDP and voltage even more, the wattage can go up. To 350W even.
My gtx680 is supposed to use 175W max.

I now wonder if my PSU can deal with the extra 75W-100W if I buy a GTX980Ti.

Current system:
i5-3570K@4.0GHz, ASRock Z77 Extreme4, gtx680, 8GB of ram.
PSU: Super Flower Golden Silent 500 W

I have an almost silent system. I don't want to change that.
So I have a water-cooled CPU and GPU.
And a fanless PSU.
The PSU is supposed to be pretty good.
Two reviewers call this the best fanless PSU they ever tested. And one of the best PSU over all. Over 90-93% efficiency at all power usages.

Tech PowerUp review: http://www.techpowerup.com/reviews/SuperFlower/SF-500P14FG/9.html
SilentPCReview: http://www.silentpcreview.com/Fanless_PSUs_Kingwin_STR-500_Silverstone_ST50NF
(Note, the Kingwin Stryker STR-500 is basically the same PSU as the Super Flower).

I measured the power usage of my current system.
I used am Energy Savings Meter. Plugged it in my wall-socket. Plugged my system in the meter.

Power use at idle: 60W-70W.
Power use when loading the CPU (e.g. Prime95 on 4 cores): pretty stable, ~145W.
Power use when playing games (e.g. GTAV or TW3): 150W-250W. Peaks of 350W some times.
Power use when running Prime95 + FurMark (1.15.2.2): 250W-350W. Once a minute I see a peak over 400W. Usually 410W-420W. Record was 440W.

Suppose I upgrade my gtx680 to a gtx980ti, to a slightly overclocked one. (Like EVGA SC running at 1,102GHz/1,19GHz). That one should use 275W max. That's 100W more than my current gtx680.

One think to note is that measured wattage at the wall-socket is higher than the actually wattage delivered to the pc-components. Let's assume efficiency is 93%. (It's very close anyway. 91.12% at 110V, which will be close to 93% on 220V. I am on 220V, btw). That means that if I see 538W at the wall, my system will be using 500W. 538W is the max for my system.

So the gtx980ti might use 100W more than my gtx680. When taking efficiency into account, that means my system might draw 108W extra from the wall. Let's modify my currently measured values with that extra 108W.

Idle: is now 60W-70W. Will probably stay similar, as Im not using my videocard. In the worst case, 170W-180W. Way under 538W. Not a problem.
When running cpu-intensive applications: is now 145W. In the worst case, 250W. Not a problem.

During games: 150W-250W usually. Peaks to 350W.
This will now be: 260W-360W. Still not a problem.
Peaks will go from 350W to 460W. Still under the 538W max. Should not be a problem.

During stress test with Prime95 and Furmark: 250W-350W, peaks to 440W.
This is where the problem is.
New average usage will be 360W-460W. With peaks to 550W.
550W is more than the theoretical 538W that my PSU can deliver.

However, there are 2 factors that might make this less bad than it looks.
1) This high wattage is only reached during artificial stress-testing. If I never run FurMark, and only play games, it looks like I will always stay under 460W.

2) The problematic max is only during peaks. I see those peaks maybe once a minute at the max. PSUs are supposed to be able to deal with short peaks in power use.

Look at this page:
http://www.techpowerup.com/reviews/SuperFlower/SF-500P14FG/5.html
Look at the chart: Voltage Regulation and Efficiency Measurements

The Tech Powerup tester has tested the SuperFlower up to 600W ! That's internal use. The use at the wall-socket was 660W. Apparently the PSU was able to deal with that without any problems. If it can deal with 660W wall-usage over a longer period of time, it should be able to deal with 360W-460W and peaks of 550W. It seems that even during the hardest stress-tests, I will still stay 20% under the max capacity of the PSU. During regular gaming, I even stay 40%+ under max capacity.


However, I am not an electrical engineer.
And I am not sure this simple math is correct.
And I might overlook something fundamental.

So, what do you think ?
Would my 500W SuperFlower Fanless PSU be good enough to replace my gtx680 with a gtx980ti ?

Thanks in advance.
--
(And for the record: no, I will not replace my PSU. And also: I know the standard answer will be: "just buy a 800W PSU, so you'll be safe". This time I am measuring things, and I want to talk more precise numbers).

 

[Flapdrol1337]

I think you'll be fine as long as you don't run prime and furmark at the same time.

Could always mount a slow fan on top of the superflower if you want to be safe, it's probably a more powerful psu inside, with a 500W sticker so it can be fanless.

 

[KGBinUSA]

680 can spike to 230 watts, while 980ti can spike to 300.

If you bought a 980 TI, I would invest into an AX series Corsair PSU. It does have a fan, but it does not kick in until the PSU actually needs cooling. AX860i should not kick in at all with your current specs.

 

[cruzinforit]

You should be fine. The Golden Silent series is a fanatastic power supply, and it can easily handle a bit over 500W with proper ventilation. I wouldn't make a habit of running prime95/linpack and furmark for hours on end all the time, but other than that I think you are just fine on that power supply, so long as it is properly ventilated.

Keep in mind however, that since it is a fanless power supply, you are really going to be heat loading those capacitors. It uses Nippon/United chemi-con caps, which are top shelf stuff, but heat is what damages them over time. Should this really be a concern for you? Likely not, but it's something to consider.

 

[DigDog]

i wouldnt count on that PSU to be able to cope with 550w every day. maybe for a short run, but eventually it will blow, possibly taking the mobo with it.

today you can get astounding quality PSUs, around 700w, which will always have your PC within the ideal efficiency spread, and due to the higher wattage and better components, will likely never get hot and last 10 years.

my thoughts.

 

[cruzinforit]

i wouldnt count on that PSU to be able to cope with 550w every day. maybe for a short run, but eventually it will blow, possibly taking the mobo with it.

today you can get astounding quality PSUs, around 700w, which will always have your PC within the ideal efficiency spread, and due to the higher wattage and better components, will likely never get hot and last 10 years.

my thoughts.

See, I agree with that. But I think unless he is running furmark and linpack all the time, I doubt he will often see above 500W very often. His estimate of average being around 350W is around my estimates as well. 400 tops for an average, which is well within the capabilities of his PSU as long as it's well ventilated.

 

[Gryz]

Thanks for all the replies.

No, I will not buy another PSU. I already wrote that. The number 1 property of my system is that it is (almost) silent. And the noise when idle is pretty much the same as the noise under high load. When I built this system, I first bought a Seasonics 1050W hybrid PSU. That PSU was supposed to not spin its fan until at 30% load. That's 300W, which I hardly even reach during gaming. But the reality was: even when just browsing the web the psu-fan would often start spinning. Useless PSU, for me. I sold it, and bought the SuperFlower. The SuperFlower is now the core building block of any system I'll build in the future. Not only because it's silent, but also because it's ~93% efficient under high load.

I'm keeping the heat in consideration, Cruzinforit. My system is watercooled (gpu and cpu) with a custom loop. I got an old Resorator1 in the loop. So I have 3 liters of water in my loop. It takes almost an hour for that water to even heat up. In the past I have ran without a radiator (the Resorator did the (passive) cooling). And without casefans. But since I got my gtx680 I added 2 casefans (front and back). And a radiator at the top with 2 fans blowing heat out of my case up through the radiator. All fans run at 500rpm. But the overall system is good enough to keep everything cool. The PSU is at the bottom in my Fractal Design case, so it's not taking any heat from any other component. So overall, I'm pretty confident about the cooling.

As I wrote, when I play games, the measured power-draw at the wall-socket is 150W-250W, with occasional spikes to 350W. When my videocard's TDP goes from 175W to 275W, I expect an increase of total system power with about 100W (a little more when considering PSU efficiency). That would still make it only 250W-350W constant, with spikes to 450W. Of course I would not run Prime95+FurMark anymore, and certainly not for long perioids.

I just wanted to know if "PSU does 500W" means that it can do 500W constantly with short peaks above that. Or that it means the system will reboot when I get peaks above 500W. It seems it should be able to deal with those peaks just fine. Good to know.

I still haven't decided whether I'll actually buy a gtx980ti.
But at least I now know I can, if I wanted to.
Thanks all.

 

[Ayah]

the manufacturer only guarantees 500W continuous with no guarantees on peak performance.

as long as you don't trip (assuming correctly functional) OCP, you should be fine but it's definitely not recommended.

from what I've seen, almost all "premium" (think seasonic, superflower, actual server PSUs from delta etc) power supplies are slightly overdesigned for their rated power output. this is probably to account for worst case manufacturing deficiencies so I guess that could give you some comfort.

but since I'm conservative, I wouldn't want to run at any load above it's rated output performance.

 

[cruzinforit]

Thanks for all the replies.

No, I will not buy another PSU. I already wrote that. The number 1 property of my system is that it is (almost) silent. And the noise when idle is pretty much the same as the noise under high load. When I built this system, I first bought a Seasonics 1050W hybrid PSU. That PSU was supposed to not spin its fan until at 30% load. That's 300W, which I hardly even reach during gaming. But the reality was: even when just browsing the web the psu-fan would often start spinning. Useless PSU, for me. I sold it, and bought the SuperFlower. The SuperFlower is now the core building block of any system I'll build in the future. Not only because it's silent, but also because it's ~93% efficient under high load.

I'm keeping the heat in consideration, Cruzinforit. My system is watercooled (gpu and cpu) with a custom loop. I got an old Resorator1 in the loop. So I have 3 liters of water in my loop. It takes almost an hour for that water to even heat up. In the past I have ran without a radiator (the Resorator did the (passive) cooling). And without casefans. But since I got my gtx680 I added 2 casefans (front and back). And a radiator at the top with 2 fans blowing heat out of my case up through the radiator. All fans run at 500rpm. But the overall system is good enough to keep everything cool. The PSU is at the bottom in my Fractal Design case, so it's not taking any heat from any other component. So overall, I'm pretty confident about the cooling.

As I wrote, when I play games, the measured power-draw at the wall-socket is 150W-250W, with occasional spikes to 350W. When my videocard's TDP goes from 175W to 275W, I expect an increase of total system power with about 100W (a little more when considering PSU efficiency). That would still make it only 250W-350W constant, with spikes to 450W. Of course I would not run Prime95+FurMark anymore, and certainly not for long perioids.

I just wanted to know if "PSU does 500W" means that it can do 500W constantly with short peaks above that. Or that it means the system will reboot when I get peaks above 500W. It seems it should be able to deal with those peaks just fine. Good to know.

I still haven't decided whether I'll actually buy a gtx980ti.
But at least I now know I can, if I wanted to.
Thanks all.

You should be 100% ok if you do.