Differences: Reference Versus Aftermarket
The Radeon HD 5870 is currently AMD's most powerful single-GPU graphics solution. It is 11+ inches (28 cm) long, requires two physical expansion slots, and covered by a plastic shroud that also serves as an air duct. A radial fan on one end of the card pushes air across the GPU cooler, and the heated air leaves the system through the opening vents at the card’s slot cover. This cooling concept works pretty well, as it not only provides effective graphics component cooling, but it also helps to remove warm air from the inside of your PC. Entry-level graphics solutions can be cooled at very low noise, while high RPM speeds of the radial fan help to keep high-end graphics solutions cool.
MSI’s Lightning version is slightly shorter at 26 cm, but it still requires two slots for installation. The first key difference relates to power, as MSI requires two 8-pin PCIe connectors instead of two 6-pin auxiliary power connectors on the reference board. However, the package includes the necessary adapters in case your power supply doesn't include two 8-pin outputs.
The second key difference is the cooling solution, which employs five heat pipes and two 75 mm fans. Heat pipes are best if you want to distribute heat across a larger surface. The dual fans are able to run at a slower rotation speed than AMD's blower, providing a more distributed air flow across the card and less total noise. The disadvantage is the absence of a cooling duct, which may be an issue especially now, in the summer, because the two fans essentially blow hot air around in your case without getting rid of it. Thus, it is important to ensure adequate system ventilation using additional fans.
AMD's reference Radeon HD 5870 clock speed is 850 MHz, while the video memory runs at 1,200 MHz. In general, vendors seem to take one of two different approaches to overclocking. Factory-overclocked cards either come with slightly increased GPU speeds and an overclocking tool to try your luck at squeezing out more frequency (at your own risk). Or, there are aggressively-overclocked models (GPU) with slight memory clock optimizations as well.
In everyday operation, it makes only limited sense to overclock the graphics chip alone. Therefore it is important to use tools that allow checking the impact of overclocking settings in real 3D workloads. MSI’s Kombustor is one possible tool. We found that, using this tool, you have to restart your system once aggressive settings result in a corrupted image (see screenshot above), even if you turn clocks back down.
MSI’s R5870 Lightning runs factory-overclocked, but leaves serious overclocking to the customer: the GPU runs at 900 MHz (a mere 50 MHz increase) and the memory at 1,200 MHz, the same as AMD's reference design.
The center of the MSI overclocking world, as interpreted by MSI, is the Afterburner tool. It effectively replaces Riva Tuner and works with most graphics cards models. We like that it’s very functional and easy to use. Effectively, we’d compare it to EVGA's Precision tool for Nvidia. Afterburner is equivalent, but it can serve AMD and Nvidia graphics products. The current version (1.61) requires AMD's Catalyst driver and is actually based on Riva Tuner;'s features. Since the tool is so easy to use, we ended up using it for all our overclocking testing.
