We have overclocked a ton of AMD Radeon HD 7000 series over the past six months, so let’s jump head first into this.
The Sapphire HD 7970 OC Edition is already factory overclocked and comes clocked at 1000MHz on the core and 1450MHz on the memory from the start. The reference AMD Radeon HD 7970 that AMD sent us was clocked at 925MHz core and 1375MHz memory, so this card is already overclocked by 8% on the core and 5.5% on the memory. By using CATALYST Control Center (CCC) you can raise or lower the clock frequencies within the parameters set by AMD. For this card AMD set limits for this particular BIOS to 1500MHz on the core and 1950MHz on the memory.
We know this card can do well over those limits, but we used CCC anyway and found that with the power control settings maxed out at 20 we could hit 1145MHz on the core and 1500MHz on the memory before any artifacts started to show up in our benchmarks. This is a great overclock as it is 220MHz or 24% over the reference card clock speed!
To get the most out of the Sapphire Radeon HD 7970 OC 3GB video card we will be using the latest version of SAPPHIRE’s TriXX overclocking utility (v4.3.0).
TriXX allows tuning of the GPU voltage as well as core and memory clocks, whilst continuously displaying temperature. You can see the default voltage on our card is set to 1112mV.
Manual control of fan speed is supported, as well as user created fan profiles and the ability to save up to four different performance settings.
The TriXX utility allows for much higher clock speed adjustment since it has GPU voltage adjustment. We didn’t play around with overclocking the memory, but we cranked up the voltage to 1287mV and was able to reach 1310MHz on the core clock speed!
This is the first time that we have been able to break 1300MHz on any AMD Radeon HD 7970 graphics card and we have a good half a dozen of them here that we have been tinkering on. Our highest stable overclock was 1310MHz on the core clock and 1500MHz on the memory. This is an increase of 385MHz or 42% on the core clock! Not a bad overclock that was achieved by using a free overclocking utility and no physical mods or extreme cooling measures!
Let’s take a look at some Futuremark 3DMark11 on the performance preset to see how the overclock helped performance.
SAPPHIRE HD 7970 OC Edition at 950MHz core and 1425MHz memory:
SAPPHIRE HD 7970 OC Edition at 1145MHz core and 1500MHz memory:
SAPPHIRE HD 7970 OC Edition at 1310MHz core and 1500MHz memory:
We tried out this overclock with Futuremark 3DMark 11 on the performance preset and saw the score go from P8560 to P10738, which is a 25.4% improvements from the cards factory overclocked settings. The SAPPHIRE HD 7970 OC Edition is an amazing overclocker and the Dual-X GPU cooler does an excellent job at keeping the card cool and quiet when overclocked at 1310MHz! Overclocking turns this card into what feels like an entirely different video card, so be sure to try it out!