MSI R7970 Lightning Video Card Review
MSI is launching its new flagship Radeon HD 7970 based Lightning series video card this week. This highly customized video card takes the Radeon HD 7970 and adds all sorts of features. Will the extra customizations like "GPU Reactor" add up to a stellar overclock? We'll put this video card to the test and find out.
Overclocking the MSI R7970 Lightning Video Card
Throughout this evaluation we will be using our highest stable overclock, after voltage tweaking, as a fourth video card in the evaluation for comparison, in order to fully express the amount of performance that the ASUS Radeon HD 7970 has in store.
Please remember that every video card is different and the overclocks we achieve here are not necessarily what you will be able to achieve.
The actual overclocking procedure involved increasing the GPU clock speed until errors occurred, and then backing it down until the errors stopped. Overclocking the GDDR5 memory is a bit more complicated. GDDR5 has error detection and correction technology which actually adjusts the clock-rate down in order to stop errors from happening. To overclock the memory on this video card, we simply turned the clock rate until performance diminished, and then backed it back off slowly until performance stabilized.
Overclocking without Voltage Tweaking
In this first screenshot is MSI Afterburner after installing the MSI R7970 Lightning at all of its stock settings. The stock voltage on the video card is 1174mV and core clock speed is 1070MHz. This factory overclock is an increase of 145MHz compared to the reference Radeon HD 7970 design. The memory is also 25MHz higher than the reference design at 1400MHz. In the second screenshot we see the memory's stock voltage is 1600mV and the auxiliary voltage is set to +0. Before we began overclocking, we enabled +20% PowerTune under settings in MSI Afterburner.
The first overclock that we wanted to find was without the GPU Reactor and without any voltage tweaking. Without either of these, we were able to increase the core clock speed to 1160MHz, an increase of 90MHz from the Out-of-Box settings. We also achieved an additional 25MHz on the memory, but were unable to push it past 1425MHz.
After we found our maximum overclock without the GPU Reactor, we reconnected it and proceeded to see if our maximum overclock increased at all. We were a bit disappointed to find that we only received an additional 10MHz on the core, bringing the total speed up to 1170MHz. The memory would not increase anywhere past 1425MHz either.
Overclocking with Voltage Tweaking
Our next step in the overclocking process was to utilize the Tripple Overclocking support that the MSI R7970 Lightning video card possesses. This gives us control of the Core, Memory, and Auxiliary Voltages.
The first thing that we did with voltage tweaking was maximize the Auxiliary voltages to +30mV. Then we started increasing the voltage on the Core, but ran into a stiff wall at 1190MHz. To get to this frequency we had to increase the Core Voltage to 1231mV. At this voltage we were able to keep a stable 1255MHz Core in Battlefield 3 and Skyrim, but in Mass Effect 3, Batman: Arkham City, and Deus Ex: Human Revolution the driver would stop responding or the system would crash operating above 1190MHz. Because this, we used the highest frequency that all games would handle as our highest overclock.
With the Radeon HD 7970 video card series we have seen extremely high overclocks, especially on the memory with speeds upwards of 6.9GHz GDDR5. For some reason, the MSI R7970 Lightning did not handle overclocking the memory very well. We increased voltage to 1649mV which allowed us to increase the memory's operating frequency to 1475MHz. We could not increase the memory clock above this even by maxing out the memory voltage slider.
The MSI R7970 Lightning comes with a fair factory overclock of 1070MHz core and 1400MHz memory. Our maximum overclock on the MSI R7970 Lightning was 1190MHz on the Core with +57mV on the core's voltage. The memory's maximum operating frequency was 1475MHz (or 5.9GHz GDDR5) with +49mV on the memory voltage. Compared to the reference Radeon HD 7970 design, this is an overall increase of 265MHz on the core and 100MHz on the memory. Overall, not as impressive as we would have thought.
Below is a screenshot of GPU-z after achieving our maximum stable overclock, which will be used as the operating frequency through the rest of the evaluation as a fourth video card.