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SLI 560ti

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March 10, 2012 1:39:27 PM

I am running two 560ti cards overclocked to 1000mhz on this power supply. Is 750 watts enough for that?

Other specs are:
corsair ssd
1tb hdd
amd 1090t cpu

Im running occt and my idle voltage on the 12v rail is reading 14.7 at idle. (I know that software readings are notoriously wrong)
At the same time. speedfan is reporting 10.56 so I dont trust either. I might get a multimeter and try to test it under load to be sure.

More about : sli 560ti

a c 1310 U Graphics card
a c 667 ) Power supply
March 10, 2012 2:22:19 PM

Yes a quality 750watt is good for that.
March 10, 2012 2:36:11 PM

The watt and amp usage on systems will differ, however, based on a few reviews, you are probably pushing your power supply to it's limit, which is never good. A single 560 ti needs about 300W, a second one requires about 200W on top of that. Add about 20W to each card for the over-clock and you're at 540W just for the two cards under load. Your 12v rails spec state that they can handle 650W. You have enough amps as they each need around 20A on the 12v and you have 54A. That leaves only around 210W for the rest of your system, which a 1090t (with components) can easily achieve. Luckily, these numbers are read from the wall and not what the power supply is actually pushing to the components. This means that under load you may have around 50W to spare.

If your computer is stable (no games crashing, random system restarts, slower than expected 3D performance) then you're OK for now. However, you're probably going to run down the power supply's internal components quickly. I'd rather keep a functional power supply for another build and buy a new one that can handle this computer (850W at least) comfortably. In fact, I'm running 2 x 560 ti SLI on this machine and have a 1000W PS because I like my max power draw to fall into the highest efficiency range, which is around 40% - 60% power load.
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a c 271 U Graphics card
a b ) Power supply
March 10, 2012 4:33:54 PM

Vythiel said:
The watt and amp usage on systems will differ, however, based on a few reviews, you are probably pushing your power supply to it's limit, which is never good. A single 560 ti needs about 300W, a second one requires about 200W on top of that. Add about 20W to each card for the over-clock and you're at 540W just for the two cards under load. Your 12v rails spec state that they can handle 650W. You have enough amps as they each need around 20A on the 12v and you have 54A. That leaves only around 210W for the rest of your system, which a 1090t (with components) can easily achieve. Luckily, these numbers are read from the wall and not what the power supply is actually pushing to the components. This means that under load you may have around 50W to spare.

If your computer is stable (no games crashing, random system restarts, slower than expected 3D performance) then you're OK for now. However, you're probably going to run down the power supply's internal components quickly. I'd rather keep a functional power supply for another build and buy a new one that can handle this computer (850W at least) comfortably. In fact, I'm running 2 x 560 ti SLI on this machine and have a 1000W PS because I like my max power draw to fall into the highest efficiency range, which is around 40% - 60% power load.

The GTX560Ti 384 core card requires 170w, what card are you thinking of? :heink: 
March 11, 2012 3:07:24 AM

Vythiel said:
The watt and amp usage on systems will differ, however, based on a few reviews, you are probably pushing your power supply to it's limit, which is never good. A single 560 ti needs about 300W, a second one requires about 200W on top of that. Add about 20W to each card for the over-clock and you're at 540W just for the two cards under load. Your 12v rails spec state that they can handle 650W. You have enough amps as they each need around 20A on the 12v and you have 54A. That leaves only around 210W for the rest of your system, which a 1090t (with components) can easily achieve. Luckily, these numbers are read from the wall and not what the power supply is actually pushing to the components. This means that under load you may have around 50W to spare.

If your computer is stable (no games crashing, random system restarts, slower than expected 3D performance) then you're OK for now. However, you're probably going to run down the power supply's internal components quickly. I'd rather keep a functional power supply for another build and buy a new one that can handle this computer (850W at least) comfortably. In fact, I'm running 2 x 560 ti SLI on this machine and have a 1000W PS because I like my max power draw to fall into the highest efficiency range, which is around 40% - 60% power load.


Thanks for the response. Today while playing ME3 with each card at ~30% load according to afterburner, I got a loud beep from my case. Of course knowing what this usually means I immediately looked over at my second monitor to see all my hardware running as cool as ever (one 560ti at 42c and the other at 50, cpu at ~25c). I have a very cool system. So now I am wondering if maybe it was the psu being overloaded, do most PSUs even have warning beeps? I had absolutely no drop in fps or stuttering at all. and it lasted about 10 secs and stopped. Oh yeah and my 1090t is OCd to 3.6 if that factors into the power draw. The only thing I can think of it being is the PSU. Anything that could overheat was well below any kind of red zone.
March 11, 2012 3:09:52 AM

Mousemonkey said:
The GTX560Ti 384 core card requires 170w, what card are you thinking of? :heink: 


He is right, ur looking at the idle consumption, if you look here, you can see his value is right on the money for load power use.
March 11, 2012 4:27:26 AM

zetorunt said:
Thanks for the response. Today while playing ME3 with each card at ~30% load according to afterburner, I got a loud beep from my case. Of course knowing what this usually means I immediately looked over at my second monitor to see all my hardware running as cool as ever (one 560ti at 42c and the other at 50, cpu at ~25c). I have a very cool system. So now I am wondering if maybe it was the psu being overloaded, do most PSUs even have warning beeps? I had absolutely no drop in fps or stuttering at all. and it lasted about 10 secs and stopped. Oh yeah and my 1090t is OCd to 3.6 if that factors into the power draw. The only thing I can think of it being is the PSU. Anything that could overheat was well below any kind of red zone.



The numbers I provided are approximate since I don't know the specifics of your system. They were also a bit on the safe side. Here's a review page that shows the entire system load of a couple of 560TIs in SLI. They aren't as over-clocked as your cards. They get 628W for their system under load. Your system is probably taking more.

Also, Try this site for another power requiremtent estimate. Take care to to include the CPU overclock data and use gtx 570s to compensate for your overclocked 560 TIs. I ran the calculator using a few guesses and it came out to 746W minimum for your computer. Give it a try and see what it gives you.

As for the Beep you heard, I can't tell you what it is without further troubleshooting. The first thing I would try is to record the overclock settings and return to 560TIs to their factory default clocks. If you no longer hear the beep, then most likely you are pushing your power supply to hard. You can also disable SLI to further reduce power consumption for your testing.
a c 109 U Graphics card
a c 111 ) Power supply
March 11, 2012 5:06:43 AM

Heck even a 620w psu can run it. Mousemonkey and I both have 620w psu's and they run our cards just fine!

Best solution

a c 503 U Graphics card
a c 1106 ) Power supply
March 11, 2012 5:08:19 AM
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For a system using two reference clocked GeForce GTX 560 Ti graphics cards in 2-way SLI mode NVIDIA specifies a minimum of a 700 Watt or greater power supply that has a combined +12 Volt continuous current rating of 52 Amps or greater and that has at least four 6-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Total Continuous Amperage Available on the +12V Rail(s) is the most important factor.

Overclocking of the two GPUs to 1000 MHz will require at least an additional 10 Amps or greater increase to the combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the GPU overclock especially if you run Furmark or OCCT GPU stress testing.

The Rosewill BRONZE Series 750W (RBR750-M), with its combined +12 Volt continuous current rating of 54 Amps and with two 6-pin and two (6+2)-pin PCI Express supplementary power connectors, is insufficient to power your system configuration with two GeForce GTX 560 Ti in 2-way SLI mode with the core clock overclocked to 1000 MHz running Furmark and with an overclocked CPU.
a c 1310 U Graphics card
a c 667 ) Power supply
March 11, 2012 12:14:47 PM

zetorunt said:
He is right, ur looking at the idle consumption, if you look here, you can see his value is right on the money for load power use.

Total system load! Explained on the Performance Analysis page!
Two cards in total pulling 298watts under gaming load http://www.guru3d.com/article/geforce-gtx-560-ti-sli-re...
a c 271 U Graphics card
a b ) Power supply
March 11, 2012 12:43:21 PM

zetorunt said:
He is right, ur looking at the idle consumption, if you look here, you can see his value is right on the money for load power use.


Actually he is not right on the money as he and that link are quoting the total system usage which, as has already been pointed out, will be different from system to system.
a c 84 U Graphics card
March 11, 2012 12:49:29 PM

yes that psu can handle that card even an good 650w psu can handle that card in sli.:) 
March 11, 2012 1:49:55 PM

Best answer selected by zetorunt.
March 11, 2012 2:10:44 PM

Vythiel said:
The numbers I provided are approximate since I don't know the specifics of your system. They were also a bit on the safe side. Here's a review page that shows the entire system load of a couple of 560TIs in SLI. They aren't as over-clocked as your cards. They get 628W for their system under load. Your system is probably taking more.

Also, Try this site for another power requiremtent estimate. Take care to to include the CPU overclock data and use gtx 570s to compensate for your overclocked 560 TIs. I ran the calculator using a few guesses and it came out to 746W minimum for your computer. Give it a try and see what it gives you.

As for the Beep you heard, I can't tell you what it is without further troubleshooting. The first thing I would try is to record the overclock settings and return to 560TIs to their factory default clocks. If you no longer hear the beep, then most likely you are pushing your power supply to hard. You can also disable SLI to further reduce power consumption for your testing.


Thanks again, you have given me a lot to think about. When I got up this morning I set out to find out where the beep came from. The second I did the OCCT stress test it sounded, and since it actually stayed on long enough, I could find it. Turns out it was from my ancient UPS. No surprises there.

So for now I am going to operate under the assumption that the PSU is sufficient, albiet pushed to its limits. As ko888 pointed out, while the wattage is fine, the amperage is lacking. But I guess thats what you get with a 3 year old roswill power supply.

Ill probably take their clock down to 880ish to give the PSU a little breathing room. Itl will get them below the amperage threshold anyway.
a c 271 U Graphics card
a b ) Power supply
March 11, 2012 2:59:00 PM

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