PCB Design, Specifications, Cooling System
The PCB design of the PowerColor card differs from the reference design developed by ATI, so what we will say below refers to the particular model of the Radeon HD 4670. This graphics card is likely to come to market in many unique versions.
The PCB is very compact thanks to the low power consumption and the 128-bit external memory bus. Of course, it is a full-profile solution and won’t fit into some low-profile system cases in which the PCI Express x16 slot is not turned around by 90 degrees. Otherwise, we can see no potential installation-related problems.
The power section of the PowerColor PCS HD4670 is simple, using a two-phase regulator with two transistors in each phase for powering the graphics core. There are additional seats on the PCB to reinforce the power circuit by adding one more transistor into each phase. The circuit is based on a uPI uP6201BQ controller. The single-phase memory voltage regulator is based on an uP6101BSA chip. The card doesn’t need to be connected to the computer’s power supply, relying on the PCI Express slot only. It means its peak power consumption is lower than 75W. We guess the card is going to require 45-55 watts but we’ll check this out shortly.
There are eight GDDR3 chips on the PCB. These are Qimonda HYB18H512321BF-10 chips with a capacity of 512Mb (16Mb x 32), voltage of 2.0V and rated frequency of 1000 (2000) MHz. The card’s memory frequency is indeed 1000 (2000) MHz, ensuring a memory bandwidth of 32GBps. That’s not high as modern graphics cards go, so we can’t expect the Radeon HD 4670 to be fast at high resolutions.
The GPU die is large as it incorporates as many as 514 million transistors. The die itself is mounted on the wafer at an angle of 45 degrees. There is no protective frame on the core. As is common with ATI’s chips, an ordinary user can only learn the manufacturing date from the chip’s marking. Here, the GPU is dated the 29th week of 2008. So, AMD has had operating samples of RV730 since mid-July.
The core frequency agrees with the official specs. It is 750MHz. The GPU has a standard configuration with 320 ALUs grouped into 64 execution modules that comprise eight execution SIMD arrays. Each such array is accompanied with four texture processors, so there is a total of 32 TMUs. The rasterization subsystem consists of eight raster back-ends. Besides, the core incorporates a full-featured video-processor (UVD 2) which, among other things, can output eight-channel HD audio via HDMI.
The card has a standard set of interface connectors, but the PCB design allow to install a HDMI connector instead of the bottom DVI-I. The card doesn’t support DisplayPort even optionally although the RV730 has this functionality even without additional translator chips. The two CrossFire connectors allow to combine up to four PowerColor PCS HD4670 into a single graphics subsystem, but this option can hardly be called for. Some gamers may want to use two such cards in a CrossFire tandem, though.
The PowerColor PCS HD4670 is equipped with a cooler from ZEROtherm hence the abbreviation of Professional Cooling System in its name. We can’t see anything extraordinary about the cooler, though. It is similar to blowers from Zalman and Thermaltake.
The RV730 doesn’t generate much heat, so the cooler doesn’t use heat pipes and its heatsink is made from aluminum. It looks stylish thanks to black anodizing. This must be the reason for the marketing folks to call it Professional. Well, we don’t have anything against this cooler. It should be able to cope with the GPU at little or no noise at all considering the size of the heatsink and the diameter of the fan. We’ll check this out in the next section of the review. The fan uses two-pin connection and probably rotates at a constant speed. Notwithstanding the translucent impeller, the fan lacks any highlighting.
The heatsink is fastened to the PCB with four spring-loaded screws. The fastening is tight. Considering the low weight of the heatsink, there is no risk of any damage to the GPU. Light-gray thermal grease is used as a thermal interface between the heatsink and the graphics core. It seems to be ZT-100 grease from ZEROtherm. Each pair of memory chips is cooled with a small individual heatsink glued with a sticky thermal pad.
The cooling system looks good. If it proved to be efficient at little noise, the title of Professional Cooling System can be considered well-deserved.