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6870CF vs 6950 Power Consumption

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  • Power Supplies
  • Power Consumption
  • Corsair
  • Components
Last response: in Components
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February 5, 2012 12:26:45 AM

I'm building a new system, and I have a Corsair HX-650W PSU, My question is I'll be keeping this PSU, and I was wondering if it could power 6870's in CF with a 2500k OC'd to 4.5GHZ, with a 1.35vcore. I will not be able to upgrade this PSU. I am hoping to go with the CF, but I don't want to blow up my PSU. Or should I jsut go with a 6950 OC it and possible Flash it to a 6970 bios. I don't think I would be able to do any OC with a 650 for 2 6870 in CF.

More about : 6870cf 6950 power consumption

a c 275 ) Power supply
February 5, 2012 1:07:33 AM

Either way you'll be fine with your current psu.
Total power consumption for 2 x 6870 in full stress is about 420W.
Which leaves you over 200W for other components.
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a b ) Power supply
February 5, 2012 1:44:00 AM

Yep. No problemo.
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February 5, 2012 1:55:08 AM

2 6870s on a 650W would be close to the limit. The video cards alone could draw ~425W, the overclocked 2500K another 150, drives, motherboard, fans etc. another 50W. That gives you a max wattage of 624 (erring on the side of caution) which I would feel is a bit close to the limit but still safe. The risk of early PSU failure due to running close to the limit would probably be higher but if you have good airflow in your case, you'd probably be safe. The 6870s would far outperform the 6950/70 (I've got 2 6870s and love them except when amd is slow getting drivers out) so if I were in your position I'd take the 6870s simply because that's a high quality PSU with 4 PCIe connectors, I wouldn't trust most other PSUs.

Out of curiosity, would you no be able to sell the 650W in order to subsidise the purchase of a more potent unit?


6870 XFire review - http://www.guru3d.com/article/radeon-hd-6850-6870-cross...


2400K power draw
- http://www.hardocp.com/article/2011/01/03/intel_sandy_b...

6970 power draw - http://www.anandtech.com/show/4061/amds-radeon-hd-6970-...

Sorry for the essay but I'm curious if anyone else has a different take on this.
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a c 275 ) Power supply
February 5, 2012 2:01:12 AM

Guru3D
"Our test system is based on a power hungry Core i7 965 / X58 based. This setup is overclocked to 3.75 GHz. Next to that we have energy saving functions disabled for this motherboard and processor (to ensure consistent benchmark results). On average we are using roughly 50 to 100 Watts more than a standard PC due to higher CPU clock settings, cooling, additional cold cathode lights etc."

"With that in mind. Our normal system power consumption is higher than your average system."
The OP's HX-650 will be fine for a SB build o'cd with 2 x 6870.
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February 5, 2012 2:15:54 AM

davcon said:
Guru3D
"Our test system is based on a power hungry Core i7 965 / X58 based. This setup is overclocked to 3.75 GHz. Next to that we have energy saving functions disabled for this motherboard and processor (to ensure consistent benchmark results). On average we are using roughly 50 to 100 Watts more than a standard PC due to higher CPU clock settings, cooling, additional cold cathode lights etc."

"With that in mind. Our normal system power consumption is higher than your average system."
The OP's HX-650 will be fine for a SB build o'cd with 2 x 6870.



Good point, that puts peak power closer to 500-550W depending on the rest of the system and well within safe draw (sometimes I read too fast :??:  )
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February 5, 2012 2:27:17 AM

Yh current psu is fine
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a c 144 ) Power supply
February 5, 2012 2:39:56 AM

Agree with davcon here.

I use the power estimates from
http://forums.atomicmpc.com.au/index.php?showtopic=264
They are based on manufacturer's data and tend to overestimate power usage a little which makes them a great "worst case" estimate.

I estimate power consumption of an OC'd CPU as TDP + 25%. This is pretty close to actual measurements.

Motherboard and RAM: 80 - 120 watts depending.

Two hard drives and an optical: 40 watts.

This gives me an estimate that is about 10 - 15% higher than what I measure with my Kill-A-Watt meter. I call that Mr. Murphy's share (ignore Mr. Murphy at your peril :) ).

So I would estimate power consumption:
Two 6870's: 20 amps peaking to 25.
CPU: 10 amps.

That is about 360 watts. (Inexpensive power meters do not respond to short duty cycle peaks - Mr. Murphy again.) Add another 160 watts = 500 watts.

Subtracting 10% puts us close to what Guru3D measured (421 watts).
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February 5, 2012 10:48:19 AM

Best answer selected by Vasquejj.
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a b ) Power supply
February 5, 2012 11:57:19 AM

This topic has been closed by Mousemonkey
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