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Power Consumption, Heat Dissipation, Noise and Overclocking

Since RV740 is the first GPU manufactured with 40nm process, it is extremely interesting to investigate its power consumption. Of course, we couldn’t miss the opportunity to check it out and used the following testbed for our experiments:

  • 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.


Click to enlarge

The results turned out absolutely shocking: the peak power consumption of our Radeon HD 4770 didn’t exceed 50W in 3D mode, while Radeon HD 4830 with the same core configuration but working at only 575MHz frequency consumed around 85W! Excellent unprecedented result! Moreover, Radeon HD 4770 has no real need for a separate power connector: the total load on both +12V power lines is a little over 47W, while the power part of the PCI Express x16 slot may provide up to 75W of power. In other words, even if we power the card solely through the PCIe x16 slot, there still will be more than enough reserves for serious overclocking. I am sure that ATI partners will soon roll out Radeon HD 4770 modifications like that, too.

The thermals of the new graphics processor matched its economical character:

 

In idle mode the temperature stayed stably around 43-44°C in an open testbed and around 52°C in a closed system case. In burn mode the GPU temperature didn’t exceed 65-66°C in both cases, at least according to Catalyst Control Center. These are excellent results, especially considering that the card is almost noiseless.

I would like to remind you that the noise measured in our lab at a 1m distance from the system case equipped with a passively cooled graphics card is 43dBA, which is a starting point for all our noise measurements. So, the results of Radeon HD 4770 turned out as follows:

The card is subjectively noiseless and the fan rotation speed is set at 32% in Catalyst Control Center.

Nevertheless, we discovered an issue with the fan rotation speed control logics of Radeon HD 4770 samples: sometime it would increase the fan rotation speed to its maximum for some reason, which is accompanied by a noise upsurge for 1-2 seconds and then the card gets quiet again. It happens pretty rarely, but always unexpectedly, which may be quite annoying. The graphics division of Advanced Micro Devices is aware of the problem, so it should be fixed in the mass production graphics cards.

Unfortunately, the official Radeon HD 4770 overclocking tools - Catalyst Control Center control panel – has very limited functionality: the maximum GPU frequency is only 830MHz, and maximum memory frequency 850 (3400) MHz.

The card worked stably at these speeds, but the 40nm GPU could definitely do better than that. And we did find a way of overcoming the unfounded limitation by slightly modifying the latest RivaTuner version. In order to teach this popular utility to work with RV740, you need to open Rivatuner.cfg file, get to [GPU_1002] section and locate the “RV770 = 9440h-9443h,944Ch” line. Then you have to add “94B3h” descriptor to it.

This method allowed us to overclock Radeon HD 4770 to 860MHz GPU and 975 (3900) MHz memory frequency. The card remained stable at these frequencies and went through the entire test session without nay failures.

It is extremely interesting not just for overclocking fans, but for everyone to see how well the newcomer will perform at higher frequencies. That is why we are going to include these results together with the performance in the nominal mode. So, let’s move on to the gaming performance analysis.

 
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