Excursus: HD 4870 – Voltage Regulator Problem
In our review of the Radeon HD 4870 we complaint already about the temperatures of the voltage regulators. Alternative cooling solutions failed also because of too high voltage regulator temperatures. With the original cooling solution we noticed critical temperatures even on the backside of the PCB in the area of the voltage regulators. But why do we repeat these issues in this article? A FurMark warning brought back old memories.
Since version 1.6.0, FurMark starts on ATI-Cards with a notice that the new Catalyst drivers slow down the tool to reduce the load. If the driver recognizes FurMark, the card won´t run at full speed anymore. However this FurMark-detection can be fooled by renaming the exe-file. To camouflage this behaviour, the driver doesn´t even lower clock-rates, the lower load seems to be achieved with driver-internal tricks.
Nevertheless to verify if a card is affected from catalyst-protection you can simply use the integrated benchmark in FurMark. We confronted AMD with this issue but didn´t get any feedback yet.
|Modell||Furmark-Benchmark (FurMark.exe)||Furmark-Benchmark (etqw.exe)|
|Radeon HD 4870||3033 Points||6219 Points|
|Radeon HD 4830||2212 Points||4134 Points|
|Radeon HD 3870||3136 Punkte||3195 Punkte|
|Radeon HD 3450||321 Points||322 Points|
On the basis of these values, we could derive that the protection only affects cards of the Radeon HD 4000 series. And one part of the HD-4000-family is the Radeon HD 4870, whose regulator-temperature had been bad in our minds. Thanks to its digital voltage regulators, the voltage-regulator-temperatures on the Radeon HD 4870 can be logged with common tools. This should confirm our concerns.
Now it is no supprise anymore, why AMD lowers the load synthetically. The card simply can not not bear the load FurMark creates. While the GPU-Temperature is absolutely uncritical, the voltage regulator temperature is not. Meanwhile the datasheet of the voltage regulator is available and Vitec specifies the temperature to 125 degrees.
Via FurMark we reached within a few minutes temperatures from about 125 degrees. Thus we can say: The Radeon HD 4870 definitly has a problem with its voltage regulators when using FurMark. Surely FurMark is a worst-case-scenario, but it points out that the voltage regulators on the Radeon HD 4870 work near its maximum specification.
We don´t want to to go beyond the scope of the article, so we will further elaborate this in separate article in near future.
Update 10.02.2009 – The Vitec-Chip is simply a multiphase-inductor. Temperatures in RivaTuner reffer to the related Volterra-Chips, which datasheets are not publicly accessible.