|PowerColor Radeon HD 5770 PCS+ Video Card|
|Reviews - Featured Reviews: Video Cards|
|Written by Hank Tolman - Edited by Olin Coles|
|Thursday, 04 November 2010|
Page 14 of 18
Overclocking the Radeon HD 5770
It took a long time for video cards to really enter into the overclocking world. Sure, you could overclock your GPU, but it took a lot of work. Then one day 3rd party software groups started releasing software utilities specifically for overclocking your video card. At first, many of these utilities were pretty ugly and difficult to use themselves. Soon after, video card manufacturers themselves joined the fray and started releasing their own overclocking software. Now many hardware manufacturers have released a utility and they are much easier to use and look a lot better. In fact, both ATI and NVIDIA have even released their own versions of overclock utilities that are available with their complete driver packages.
With the AX5770 PCS+, PowerColor overclocked the card before even sending it to the shelves. In reality, this is a testament to the durability of the Radeon HD 5770 and the Juniper core. Now, it's my personal belief that if the manufacturer can overclock a video card, even slightly, there has to be more headroom in there for me to play around with.
PowerColor doesn't offer its own overclocking utility, so I decided to stick with ATI Overdrive. There are other options out there, like ASUS iTracker, Systool, and Riva-Tuner, but for this article the ATI utility fits our needs best. The Overdrive utility lets you overclock the GPU core, the memory, and it lets you manually adjust the fan speed. Just to be safe, I cranked the fan speed up to 100%. This caused the fan on the AX5770 PCS+ to be considerably louder in our open air test bed. You would likely hear the fan pretty well even housed within a case. The maximum overclock that the ATI Overdrive utility will allow for the AX5770 PCS+ is 960MHz for the core clock and 1400MHz for the memory clock. As for now, there is no way to increase the voltage through Overdrive.
The Samsung memory modules that are found on the AX5770 PCS+ are rated at 1250MHz. On stock Radeon HD 5770 cards, they are set to 1200MHz. On the pre-overclocked AX5770 PCS+, they are set to 1225MHz. Without wanting to overdo it on the memory, I set the memory to its rated 1250MHz. My real goal here is to overclock the GPU, the memory is just a bonus.
I wanted to push the AX5770, but not overdo it right from the start, so I moved the GPU clock slider up to 900MHz to begin with. The ATI Overdrive utility has a function to test the overclock right there within the utility. Be warned, however, that the video card might pass the test in Overdrive, but still not be stable enough for some high video content. I also used to test overclocked video cards for stability using FurMark's stress test for a few hours. In the past, this was enough to weed out any instability. Unfortunately, FurMark lacks DX11 capabilities and the tessellation and other DX11 features are much more taxing on a GPU. For the time being, I am running the Unigine Heaven Benchmark at full throttle to ensure GPU stability.
At 900MHz, the PowerColor AX5770 PCS+ was rock solid, but I knew I could push it more. There was still some headroom left. In the end, 920MHz was the highest overclock we were able to achieve for the PowerColor Radeon HD 5770 PPG. This overclock represents just over an 8% increase in clock speed from a stock 850MHz Radeon HD 5770 and about a 5% increase over the already overclocked 875MHz AX5770 PCS+. While I would have liked to see a little more headroom, every video card is different. Even if you were to go out and get a PowerColor Radeon HD 5770 AX5770 PCS+ today, you would experience a different overclock-ability in it. So, you get what you get, and in reality, 920MHz isn't bad at all. Let's get into the testing now, and see how it affected our results.