2x GTX770 on 650W PSU?

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Newbie here.  I do know a bit about PCs, but this topic covers stuff I'm not sure about. 
 
I recently decided to add a second graphics card (MSi N770 4GD5/OC) to my PC, but I'm not sure if my PSU will be able to handle it. 
BeQuiet claims that the Dark Power Pro P9 650W can feed 2 cards, but I'm not sure if they were talking about anything above low-end cards. 
The card should arrive in one or two days, so I figured I'd ask for opinions now. 
 
With my current single N770, I measured the following wattages at the plug :
 
CPU and GPU idle : 90-100W
CPU maxed, GPU idle : 195-205W
CPU + GPU maxed : 360-375 W
 
Those figures were measured after 15 minutes at the same stress level (to let the temps rise and the fans ramp up), with cathodes and led strips on, my phone charging via USB and one external 2.5" HDD plugged in. 
The PC's SSDs were not really in use, but those won't add more than 10W anyway.
 
This leads me to believe that the card uses 170-175W more stressed than it does at idle.  With that in mind, MSI's 225W claim sounds fairly accurate to me. 
If I add 225W to the 375 I currently have under full system load, I'm at 600W. 
It's unlikely that I'll ever stress the PC that much, I'm not into heavy overclocking and probably won't be benching it once I did the initial stress tests. 
I highly doubt I'll ever see it go beyond 550W ... unless I'm missing something, which I probably am.

 

Outervision's eXtreme Power Supply Calculator came up with a 638W minimum, 688W recommended for the full SLI setup.
 
Am I indeed forgetting something?  Should I upgrade my PSU or would the 650W one be enough for extended gaming sessions?
 
If full specs are needed, I posted them in the  show off your setup thread.

[ddbtkd456]

750 watt minimum is recommended for dual GPU's. Also your scaling is way off considering that a single gpu and cpu run about 450 watts when maxed out, depending on if its intel or amd.

[Guest]

Total wattage will be fine (if you don't overclock too much) but it still depends on the power that the PSU can deliver on the +12V rail. From what I could find it can provide 53A on that rail, which seems appropriate for the task. I've had 2 770s running on a 680W PSU without a problem before, I'm pretty sure you will be fine. You're pretty much going for the limit of your PSU though, keep that in mind.

 

750 watt minimum is recommended for dual GPU's. Also your scaling is way off considering that a single gpu and cpu run about 450 watts when maxed out, depending on if its intel or amd.

 

<100W for the CPU and pretty much 200W for the GTX 770. Both under full load. My system with a single 770 peaked at 380W for a typical gaming load (CPU near max and GPU at 100%).

[Luke]

750 watt minimum is recommended for dual GPU's. Also your scaling is way off considering that a single gpu and cpu run about 450 watts when maxed out, depending on if its intel or amd.

 

My FX 8320/7970 used 340 watts avg during unigine valley. I tried prime and a few different programs but unigine seemed to use the most power. The Dark Power Pro P9 650W has 636W on the 12V rail and seems to be a good quality PSU. A friend of mine ran two HD 5850's overclocked with a i7 860 @ 3.8Ghz on a Antec truepower 650W for close to 3 years. I have no doubts that your power supply will be enough two add another 770, Especially if you are not overclocking.

[akron]

Newbie here.  I do know a bit about PCs, but this topic covers stuff I'm not sure about. 

 

I recently decided to add a second graphics card (MSi N770 4GD5/OC) to my PC, but I'm not sure if my PSU will be able to handle it. 

BeQuiet claims that the Dark Power Pro P9 650W can feed 2 cards, but I'm not sure if they were talking about anything above low-end cards. 

The card should arrive in one or two days, so I figured I'd ask for opinions now. 

 

With my current single N770, I measured the following wattages at the plug :

 

CPU and GPU idle : 90-100W

CPU maxed, GPU idle : 195-205W

CPU + GPU maxed : 360-375 W

 

Those figures were measured after 15 minutes at the same stress level (to let the temps rise and the fans ramp up), with cathodes and led strips on, my phone charging via USB and one external 2.5" HDD plugged in. 

The PC's SSDs were not really in use, but those won't add more than 10W anyway.

 

This leads me to believe that the card uses 170-175W more stressed than it does at idle.  With that in mind, MSI's 225W claim sounds fairly accurate to me. 

If I add 225W to the 375 I currently have under full system load, I'm at 600W. 

It's unlikely that I'll ever stress the PC that much, I'm not into heavy overclocking and probably won't be benching it once I did the initial stress tests. 

I highly doubt I'll ever see it go beyond 550W ... unless I'm missing something, which I probably am.

 

Outervision's eXtreme Power Supply Calculator came up with a 638W minimum, 688W recommended for the full SLI setup.

 

Am I indeed forgetting something?  Should I upgrade my PSU or would the 650W one be enough for extended gaming sessions?

 

If full specs are needed, I posted them in the  show off your setup thread.

I could be wrong but I'm pretty sure gpus change power consumption depending on what your doing. 

Someone once told me that I wouldn't be able to add a certain processor because the processor + everything else was about 400 watts

I have a 500watt power supply, the processor was going to add +80 but he said don't do it b/c of the things it will do

I'm just going to apply this with graphics cards as well and just say no, don't do it.

 

 

+ dbbtk said that the 750 was the minimum. 

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