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Power Consumption, Temperature, Noise and Overclocking

The Radeon HD 4890 has rather ambiguous specified power requirements. On one hand, its peak power consumption has grown from 160 to 190W in 3D applications but on the other hand, its 2D consumption is lower than that of its predecessor. We checked this out on our special testbed configured like follows:

  • Intel Pentium 4 560 CPU (3.6GHz, LGA775)
  • DFI LANParty UT ICFX3200-T2R/G mainboard (ATI CrossFire Xpress 3200 chipset)
  • PC2-5300 SDRAM (2x512MB, 667MHz)
  • Western Digital Raptor WD360ADFD HDD (36GB)
  • Chieftec ATX-410-212 PSU (410W)
  • Microsoft Windows Vista Ultimate SP1 32-bit
  • Futuremark PCMark05 Build 1.2.0
  • Futuremark 3DMark06 Build 1.1.0

Following our standard procedure, the 3D load was created by the first SM3.0/HDR test from 3DMark06 running in a loop at 1600x1200 with forced 4x FSAA and 16x AF. The 2D load was emulated by the 2D Transparent Windows test from PCMark05. The PowerColor HD4890 has a pre-overclocked core frequency, so we had reduced it to the standard 850MHz in Catalyst Control Center before the test.

Click to enlarge

ATI’s new product surprised us really. It is far more economical in 2D mode than its predecessor, but also consumes 10W less than the Radeon HD 4870 under load! This result was repeatable with a variation within 0.7W. So, the card’s peak power draw was never higher than 121W! The innovations in the RV790 design such as the decoupling circuitry and the revised internal power distribution system are very beneficial for the not-quite-economical RV700 architecture. The distribution of load among the individual power lines has changed considerably since the Radeon HD 4870. The load on the internal +12V line has lowered but the load on the bottom power connector has grown up. Following Nvidia, ATI has improved the algorithm for automatic reduction of the GPU frequency in 2D mode. In this case the GPU frequency goes down not to 300MHz as it used to before, but even lower, to 240MHz. The memory frequency in this case remains intact.

Generally speaking, 120.3 watts is not a record. It is better than the result of the GeForce GTX 285 but far worse than the power consumption of the GeForce GTX 260 Core 216. The power consumption of the GeForce GTX 275 is expected to be somewhere in between and comparable to that of the Radeon HD 4890.

Surprisingly enough, the Radeon HD 4890 was not very hot. The GPU temperature varied from 55 to 68°C only. For comparison, the core of the Radeon HD 4870 could be as hot as 90°C under load! The numbers indicate an improvement in the power efficiency of the RV790 processor, but what about the cooler’s noise?

The reference point of our noise test is 43dBA. This is the amount of noise at a distance of 1 meter from the working testbed equipped with a passively cooled graphics card. When we installed our Radeon HD 4890, we got the following results:

The card is very noisy when you turn the system on, but then drops the fan speed to near-silent level. The fan accelerates as the GPU load increases, making the card audible in the noise produced by our testbed which is not quiet by itself. It is mostly a characteristic rattle that must have been produced by the fan’s bearings. Anyway, we must admit that the Radeon HD 4890 is quite comfortable in terms of noisiness. Its cooling system behaves like the one of the Radeon HD 4870. Not a surprise considering that they are almost identical.

The official guide to overclocking the Radeon HD 4890 suggests to set the fan speed slider at 100% in Catalyst Control Center.

Well, this guide must be intended for deaf computer enthusiasts because if you follow the advice, the card sets the record of producing the highest noise we’ve ever heard in our tests. Over 64dBA at a distance of 1 meter from the system case is too much to be near the computer for a long time unless you wear protective earpieces.

We don’t think anyone will use the guide’s recommendation and so we ignored it in our overclockability test. We tested the Radeon HD 4890 with its fan management system set to automatic mode. Despite this, we achieved an impressive result on our first attempt.

Without using any additional overclocking tools or methods we conquered the 1GHz peak! For example, we had had to volt-mod the much simpler Radeon HD 3870 and increase its GPU voltage from 1.3V to 1.71V in order to achieve the same clock rate. The memory chips were stable at 1200MHz, which is equivalent to 4800MHz for GDDR5 memory. ATI’s initiative of launching the Radeon HD 4890 OC as an individual product makes sense indeed. The new card boasts excellent overclockability and full stability. It worked without problems at the increased frequencies and passed all of our tests. Therefore we will publish the test results it achieved at both default and overclocked frequencies.

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