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Enough amps for a EVGA GTX 760 SC

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  • Gtx
  • EVGA
  • ATX
  • Graphics
Last response: in Graphics & Displays
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December 23, 2013 4:19:52 PM

Ok I'm not familiar with the info on PSU's so I wanted to confirm that the AZZA psaz-cp700 provides enough amps. I see it has 32A on the max output current on the psu's sticker, and the card requires 30 amps.

More about : amps evga gtx 760

December 23, 2013 5:26:51 PM

Amps is not what really matters with a PSU, it's Watts. Depending on the rest of your system a 550 or 600 watt PSU will handle a GTX 760 with plenty to spare.
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December 23, 2013 5:47:56 PM

My specs are
Case: NZXT Apollo
CPU: Intel i5 3570K
GPU: Power Color HD 7850
Mobo: Asus P8Z77-V LX
RAM: 4x2GB
PSU: AZZA 700 watt
Fans: 120mm LED fan
OS: Windows 7
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December 23, 2013 6:05:22 PM

lowguppy said:
Amps is not what really matters with a PSU, it's Watts. Depending on the rest of your system a 550 or 600 watt PSU will handle a GTX 760 with plenty to spare.

This is not true at all. The system must not exceed the maximum rail amperage on each rail type AND it must not exceed the maximum total wattage on the power supply. Not only that, but calculating based on wattage of the power supply alone will result in wrong numbers: either you end up with a power supply that is way, way beyond what you really need or the power supply has a high wattage, but not enough power on the rails you need (so actually ends up not having enough power).

nmd68 said:
Ok I'm not familiar with the info on PSU's so I wanted to confirm that the AZZA psaz-cp700 provides enough amps. I see it has 32A on the max output current on the psu's sticker, and the card requires 30 amps.

I'm not really the best person to ask on how to calculate the rails precisely, but I'll give it a shot.

The GTX 760 consumes around 158W at full load according to this page: http://www.techpowerup.com/reviews/Gigabyte/GeForce_GTX...
That's maybe 13amps on the 12v rail (158W/13) ... but then factor in the power supply efficiency. Let's say the power supply is 70% efficient, worst case (so we'll add 30% to the numbers).... and also factor in that you don't want to be running at max.
13amp + (30%) = 17amps ... then add padding so you don't run at max.

After that, you have to factor in how much the CPU and fans draw from the 12v rail. Fans take up very little, so focus on the CPU.
Look at actual power draw tests to see here and factor in 30% for an inefficient power supply.
Also add padding so you don't run at max.
This thread has some links to power draw tests from Anandtech on some CPU: http://forums.evga.com/tm.aspx?m=1705045#1705368


Also, you might consider that EVGA suggests 30amps on the 12v rail for the GTX 760: http://www.evga.com/Products/Product.aspx?pn=02G-P4-276...
What I don't know is if this number includes padding for CPU, case fans, and power supply efficiency or if it is a raw number not including CPU, fans, etc.... If it is a raw number not including CPU, then your power supply won't work for sure.
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December 23, 2013 6:26:26 PM

Ok, I left out one big thing. You gotta factor in hard drive and CD drive draw as well. Told you I wasn't the best person to answer this. :)  I used to use a rather good power calculator that calculated individual rails, but I don't know where it is anymore. :( 
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December 23, 2013 6:34:34 PM

It is very difficult to exceed the amperage of a PSU without some serious effort, and even then you'll probably exceed the wattage capacity first. PSUs are generally built to provide enough amps for their rated Watts. If you're buying a separate PSU (rather than some no-name OEM PSU that comes with the case) then you really don't need to look at Amps until you get into multi-GPU configurations.

Regardless, the PSU you listed will be just fine.
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December 23, 2013 6:52:57 PM

nmd68 said:
My specs are
Case: NZXT Apollo
CPU: Intel i5 3570K
GPU: Power Color HD 7850
Mobo: Asus P8Z77-V LX
RAM: 4x2GB
PSU: AZZA 700 watt
Fans: 120mm LED fan
OS: Windows 7

Are you sure it is 32amps on the 12v rail? Searching for that model returns something different.
Anyways, if it is really 32amp, then it looks like you do not have enough power for safe operation.

Consider this:

Intel i5 3570K = 77W TDP (http://ark.intel.com/products/65520)
GTX 760 = 158W in testing (http://www.techpowerup.com/reviews/Gigabyte/GeForce_GTX...)
1-2amp for fans
... putting that into 12v rail terms:
CPU 7amp * (30%) = 10amp
GPU 14 * (30%) = 19amp
fans 2amp
Total: 31amp ... then add a buffer (whatever you think) so you don't run at max
Then you ALSO, need to add hard drive(s) and CD drive(s).

Conclusion, you don't have enough power for safe operation (and maybe not enough for full load); it might work, but could get unstable under heavy load or cause the power supply to fail sooner.

On the other hand, if I spec things out according to what EVGA says:
CPU = 10amp
GPU = 30amp (per EVGA's recommendation -- even if it might be total system)
Fans = 2amp
Total: 42amp ... then add a buffer so you don't run at max and also add the hard drives and cd drives
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December 23, 2013 7:02:07 PM

lowguppy said:
It is very difficult to exceed the amperage of a PSU without some serious effort, and even then you'll probably exceed the wattage capacity first. PSUs are generally built to provide enough amps for their rated Watts. If you're buying a separate PSU (rather than some no-name OEM PSU that comes with the case) then you really don't need to look at Amps until you get into multi-GPU configurations.

Regardless, the PSU you listed will be just fine.

Ah thanks for bringing that up. It seems the newer power supplies (and the good old models as well?) are able to provide almost as much watts to the 12v rail as they are to the entire system meaning you wouldn't have to check 12v rails on those power supplies. So, that's good to know; thanks.

However, in the case of nmd68's power supply, if he is really limited to 32amps (can you please double check this nmd68?), that's not a very safe amount for the system he is considering.
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December 23, 2013 7:52:46 PM

This is what is on the PSU's sticker

AC Input: 115v/230v 10/5A 50~60Hz +5V & +3.3V combined 200W

DC Output: +3.3V +5V +12V +12V -12V +5VSB

Max Output: 24A 32A 21A 22A 0.6A 2.0A

Min Output: 1.0A 1.0A 0.5A 0.5A 0.0A 0.1A

Total Output: 700W
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December 23, 2013 9:40:59 PM

Yeah that's 32 amps on one 12v rail, with a second pushing 21 (plus all that little stuff like fans and storage separate) so between the ancillary power connectors and the PCI-E slot's share of the motherboard's power you're all set.
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December 23, 2013 9:55:20 PM

Uh, no, that's 32A on the 5V line. The two 12V lines are 21A and 22A.

Even though there's a lot of bad info in this thread, the power supply will handle a GTX760. My 430W handles a GTX760.
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December 23, 2013 10:27:12 PM

NVidia requirements is BS...NVidia assumes that you have a generic psu running 2 hdds...
as the previous comment said a 430W bronze certified psu can run 760 as long as you don't have many hdds and fancy pcie devices around...
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December 23, 2013 10:49:34 PM

Even so that's 43 between the two +12v rails, which is plenty.
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December 24, 2013 5:05:23 AM

Just got 1 segate 2TB HDD, then I might as well mention a segate 1TB external USB 3.0, linksys wireless adapter, thermaltake esports challenger pro keyboard and black element mouse and Logitech hd 720p webcam
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December 24, 2013 6:13:33 AM

yeah, most of those peripherals (key,mouse,cam) don't make much difference. typically you can say that an internal HDD takes 10W, an external HDD takes 5W or has it's own separate power supply

the main power hogs are the CPU (50W-125W for the most common ones), and graphics cards (85W-250W for the majority). so even an average 450W power supply should be able to handle a single midrange-GPU setup with 1 hard drive, if parts are kept stock (no overclocking).
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December 24, 2013 7:29:05 AM

ok I'm gonna compare my other system which runs a 550ti fpb which need on evga requires minimum 400w with 24 amps on +12v which my psu on that system has

DC Output: +3.3V +5V +12V1 +12V2 -5V -12V +5VSB

Max Output: 28A 30A 18A 18A 0.8A 0.8A 2.5A

The system runs fine even when i overlclock the card a bit
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December 24, 2013 12:15:39 PM

If you are curious, here's the raw numbers based on what benchmarking sites report and not from reading spec sheets.

base system + CPU stress test: power tested in AC (at wall)
121W(AC) @ 83 efficiency http://www.tomshardware.com/reviews/core-i5-3570-low-po...
99W(AC) @ 90? efficiency http://hexus.net/tech/reviews/cpu/38421-intel-core-i5-3...
109W(AC) @ 82-85 efficiency http://www.xbitlabs.com/articles/cpu/display/core-i7-37...
121@83 > 101(DC)
99@90 > 89(DC)
109@82 > 89(DC)

power draw in DC for the GTX 760 only
160W(DC) http://www.tomshardware.com/reviews/geforce-gtx-760-rev...
161W(DC) http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_7...
168W(DC) (for the EVGA GTX 760 SC) http://www.techpowerup.com/reviews/EVGA/GTX_760_SC_ACX_...

So taking approximately 100+168 DC power draw and assuming the worst case (all are going off the 12v rail), you get:
23 amps on 12v rail worst case scenario for base system + CPU + video card (not including hard drive and cd drive)
Based on the benchmarks, you would be safe with 42 amps.
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January 1, 2014 2:18:50 PM

Installed the card last night and works perfectly, only thing was that I had to use the power cable adapters that came with the card since my PSU has 2 6-pins and no 8-pin
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