Setup | Power consumption
Hardware installation
Installation of any of the AMD Radeon cards is really easy. Once the card is seated into the PC make sue you hook up the monitor and of course any external power connectors like 6 and/or 8-pin PEG power connectors. Preferably get yourself a power supply that has these PCIe PEG connector native (converting them from a Molex Peripheral connector anno 2010 we feel is a no-go).
Once done we boot into Windows, install the latest ATI Catalyst drivers and after a reboot all should be working. No further configuration is required or needed unless you like to tweak setting, for which you can open the Catalyst Control Center.
Power consumption
Lets have a look at how much power draw we measure with this graphics card installed.
The methodology: We have a device constantly monitoring the power draw from the PC. We simply stress the GPU, not the processor. The before and after wattage will tell us roughly how much power a graphics card is consuming under load.
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, water-cooling, additional cold cathode lights etc.
Keep that in mind. Our normal system power consumption is higher than your average system.
Measured power consumption - 6870
- Advertised TDP = 127W
- System in IDLE = 172W
- System Wattage with GPU in FULL Stress = 291W
- Difference (GPU load) = 119 W
- Add average IDLE wattage ~ 19W
- Subjective obtained GPU power consumption = ~ 138 Watts
Bear in mind that the system Wattage is measured from the wall socket and is for the entire PC. Below, a chart of measured Wattages per card. Overall this is much higher than reference, this is due to an increased GPU voltage to allow easy overclocking and the standard higher clock frequencies.
Power Consumption Cost Analysis
Based on the Wattage we can now check how much a card like today will cost you per year and per month. We use a charge 0,23 EUR cent (or dollar) per KWh, which is the standard here.
| Graphics card | TDP in KWh | KWh price | 2 hrs day | 4 hrs day |
| Graphics card measured TDP | 0,138 | 0,23 | 0,06 | 0,13 |
| Cost 5 days per week / 4 hrs day | 0,63 | |||
| Cost per Month | 2,75 | |||
| Cost per Year 5 days week / 4 hrs day | 33,01 |
We estimate and calculate here based on four hours of GPU intensive gaming per day / 5 days a week with this card.
Recommended Power Supply
Here is Guru3D's power supply recommendation on the Radeon HD 6800 series:
- Radeon HD 6850 - On your average system the card requires you to have a 450 Watt power supply unit.
- Radeon HD 6870 - On your average system the card requires you to have a 500 Watt power supply unit.
If you are going to overclock CPU or processor, then we do recommend you purchase something with some more stamina.
There are many good PSUs out there, please do have a look at our many PSU reviews as we have loads of recommended PSUs for you to check out in there. What would happen if your PSU can't cope with the load?:
- bad 3D performance
- crashing games
- spontaneous reset or imminent shutdown of the PC
- freezing during gameplay
- PSU overload can cause it to break down
Let's move to the next page where we'll look into GPU heat levels and noise levels coming from this graphics card.
