PCB Design

The PowerColor X850 XT Platinum Edition AGP differs noticeably from its PCI Express version, particularly in the power circuitry, in the connectors, and in the interface area.

Graphics cards with the PCI Express interface can receive quite a lot of power (up to 75 watts) directly through the slot, while high-power AGP devices should receive additional power through a Molex connector (the AGP slot can only provide about 40 watts at best). That said, the power circuitry of the PowerColor X850 XT Platinum Edition AGP isn’t much more complex than that of the PCI Express version. It just includes more electrolytic capacitors. The AGP version doesn’t include a Richtek RT9173A voltage regulator, too.

For some reason ATI didn’t implement two DVI-I connectors in the reference design of the RADEON X850 XT AGP. Moreover, this possibility isn’t even an option since there’s no place for an additional TMDS transmitter on the PCB. Thus, all R481-based graphics cards that follow the reference design have to use the out-dated DVI-I + D-Sub solution. We don’t know why ATI refused to have two DVI connectors on the card even as a possibility. There’s not much sense in this limitation because monitors with the analog interface can be easily connected to DVI-I outputs via appropriate adapters. But maybe it is just another hint that the AGP interface is too old? Well, PCI Express versions of the RADEON X850 need two DVI-I connectors just for the multi-GPU CrossFire technology to work, because a portion of the image is transferred from the slave card to the composition engine across this interface (for more details see our article called ATI Crosses the Swords: Multi-GPU CrossFire Technology Previewed).

The cooling system deployed on the PowerColor X850 XT Platinum Edition AGP is quite ordinary: it is the same dual-slot cooler with a copper heat-spreader, a blower, and a plastic casing. The air from the inside of the system case is blown through the heat-spreader and is then exhausted to the outside. The heat-spreader is made from a solid piece of copper. Its sole touches the GPU surface through a layer of thick gray-colored thermal paste. The memory chips contact the aluminum base of the cooler through special elastic pads. As we have already said in our reviews, the efficiency of the new reference cooler from ATI is very high, while the smart control over the speed of the blower allows to keep the noise low, unlike with the reference cooling system of the GeForce 6800 Ultra, for example.

The memory chips at the reverse side of the PCB are cooled with a simple L-shaped aluminum plate which becomes rather hot at work (not surprising, considering the high frequency the chips are clocked at). But it does its job right. At least we never had any failures due to memory overheat when testing the PowerColor card as well as any other model from the RADEON X850 family.

The PCB carries 1.6ns memory chips from Samsung. It means the memory can work at 600 (1200DDR) MHz, but it is actually clocked at 590 (1180DDR) MHz on this card, the latter frequency being the default one for the RADEON X850 XT Platinum Edition. The graphics processor works at 540MHz, like in the reference design. Besides other things, the PowerColor X850 XT Platinum Edition AGP is equipped with a Rage Theater chip for capturing video from external sources. The Rage Theater is a rather old solution, using 8-bit ADCs, but it will suit well for digitizing your VHS recordings, for example.