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Sapphire RADEON 9600 XT 128MB Ultimate Edition

The Ultimate Edition of RADEON 9600 XT from Sapphire features an original design and carries a passive cooling system consisting of two aluminum heatsinks connected by a heat pipe:

This construction becomes very warm during operation. The cooling might be more efficient if the big metal sticker with the Sapphire logo on the face side of the PCB didn’t cover the heatsink ribs, and the heatsinks themselves were better suited for working without air cooling (that is, if they had needles instead of ribs).

The VPU voltage regulator on this device is based on RT9202 controller from RichTek. As usual, we need to change the ratio of resistances in the feedback circuit to reduce the power supply voltage.

Internal circuits and I/O buffers (VDD and VDDQ) of the graphics memory chips are supplied with power by impulse regulators on Intersil ISL6522 and RichTek RT9202 chips, respectively. Again, the method remains the same: find the resistors in the feedback circuits and solder up additional resistors to them to change the resistances ratio in the desired way.

The regulator for the termination circuits is based on RT9173 chip from RichTek. It takes VDDQ as the basic voltage, so you don’t have to do anything – VTT changes with VDDQ.

The following snapshots show you where the VPU and memory voltage regulators are and where I put additional resistors:

  

  

RADEON 9600 XT chip gives out relatively little heat, although has the highest frequency of all RADEON 9xxx series chips: it has fewer transistors than R300/R350, it is manufactured with finer 0.13-micron technology and it works on only 1.3V voltage.

 

Nominal Voltage, V

Reduced Voltage, V

VPU

1.30

1.15

VDD

2.90

2.53

VDDQ

2.79

2.48

VTT

1.39

1.24

The graphics chip voltage was reduced by 11.5% and it was stable at its original frequency, 500MHz. The graphics memory on the RADEON 9600 XT also works at a high frequency, so I only reduced the voltages of the internal circuits and I/O buffers by 12.7% and 11.1%, respectively.

The card is ready for the tests:

  

RADEON 9600 XT features an integrated thermal diode, so the temperature measured for the VPU in the following diagram is very accurate:

RADEON 9600 XT dissipates little heat, and the cooling like the one we see in the Sapphire card handles this heat dissipation well enough: 66°C under workload is an acceptable result.

By reducing the voltages we make the graphics processor and memory cooler by 3-4°C in the Idle and by 4-6°C in the Burn mode. Not much, actually. If the cooling system were more efficient and the graphics chip warmer, the effect of the modification would be more conspicuous.

 
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