Radeon HD 5770, Radeon HD 4890, And GeForce GTX 275 Overclocked

MSI R4890 Cyclone SOC: Super Overclocking

Click the image below to launch the image gallery of the MSI R4890 SOC.

Performance-wise, the Radeon HD 4890 is roughly comparable to the GeForce GTX 275. Again, MSI’s take on this card is geared completely towards overclocking, sporting 8mm heatpipes, a brawny 95mm fan, as well as "military-grade components" that can withstand higher temperatures and promise a longer life expectancy. MSI clocks both the GPU and the memory of its OC edition at 1,000 MHz rather than at 850 (GPU) and 975 MHz (memory). Thus, the graphics chip is running 17.6 percent over reference speed, while the memory speed only sees an increase of 2.6 percent. This is one of the reasons why the Radeon HD 5770’s overclocking results were so surprisingly good--its GDDR5 memory achieved more than 1,400 MHz

Again, the clock rates are hard-coded into the card’s BIOS and are set independently of any driver. The fan speed profile won’t be everyone’s cup of tea, though. When the card gets warm, the fan spins up and cools the GPU, then the fan spins down in an audible manner. Repeat infinitely. This would seem like normal behavior, but the fact that it's so noticeable can be taxing.

The MSI R4890 SOC is a veritable power hog, too, causing the system to draw no less than 196 watts in (factory-overclocked) 2D mode. Under load, our test platform maxes out at 380 watts. Increasing the speed of the GDDR5 memory has a direct impact on power consumption, since the video BIOS only scales back the GPU’s clock speed in 2D mode, but always leaves the memory running at full speed. Thankfully, the Radeon HD 5770 does not exhibit the same wasteful weakness. On the other hand, the R4890 SOC’s GPU always downclocks to 240 MHz at idle, regardless of the overclock settings selected for 3D mode.

All frequencies can be changed quite comfortably from within the Overdrive section of the graphics driver. Any changes need to be tested before the driver applies them. Still, this integrated test mode is only marginally helpful. If you overdo it with the GPU clock speed, the screen will go dark, even during the test, which can only be remedied by rebooting the system. The tool was quite reliable when it came to detecting overly-optimistic memory speeds, though. Once you’ve found clock speeds that work for you, you may still need to reduce them by 10 to 15 MHz, as some games are a little more demanding under load than ATI’s testing tool.

Once of the advantages of ATI cards in general (and the MSI HD R4890 SOC specifically) is that the graphics driver is able to reset itself without requiring the entire system to be rebooted if it encounters a GPU clock speed problem. On the downside, ATI graphics cards will freeze the system if the memory speed is set too high, while an overly aggressive GPU clock speed can also cause graphical glitches and rendering errors. Since the symptoms usually manifest the other way around, this is confusing, leading you to lower the wrong clock speed until you correctly troubleshoot the actual problem. In the end, we had to fix our clock rates manually three times after the initial driver-based test. The final result was that we were able to overclock the GPU by 21.2 percent and raised the memory frequency by 9.2 percent. Thus, the Radeon HD 4890 possesses quite a bit more overclocking potential than the GeForce GTX 275.

The overclock also yields better results on MSI’s overclocked ATI card. Whereas the OC edition of the GTX 275 gained 5.5 percent performance compared to a reference card using Nvidia’s specified clock speeds, the factory overclocked Radeon HD 4890 started off with a performance advantage of 10.9 percent over its reference-clocked relative, widening that gap to 14.9 percent through manual overclocking. Even at maximum speed, MSI’s GTX 275 only managed to beat the reference card by 9.6 percent.