X-bit labs

Silence of the Radeon HD 2600: Gigabyte GV-RX26T256H Graphics Card Review (page 3)

Category: Video

by Alexey Stepin , Yaroslav Lyssenko

[ 11/19/2007 | 11:51 PM ]

PCB Design and Specifications

Being a full-featured ATI Radeon HD 2600 XT, the Gigabyte card uses a smaller PCB and GDDR3 memory instead of the reference card’s GDDR4.

Somewhat shorter than the PCB of the ATI Radeon HD 2600 XT GDDR4, it is also simpler in design, resembling the PCB of the less advanced Radeon HD 2600 Pro. The smaller dimensions will help install the card into a compact system case like a hi-fi styled case for a home multimedia system or a classic barebone from Shuttle. The PCB design may have been developed by Gigabyte, but we guess the company buys PCBs and applies an azure solder mask typical of its products.

The card not using external power supply, the power circuit components are located not in the rear part of the PCB but near the S-Video/YPbPr connector. It is based on the two-phase PWM controller Nexsem NX2415 that controls four classic power transistors. This section of the circuit delivers power to the GPU. The other section, located in the top right corner of the PCB, feeds the memory chips. The power circuit contains only three solid-state capacitors with a polymer dielectric. This is normal for the company that uses such capacitors (with better characteristics and a longer service life than classic electrolytic ones) in its Ultra Durable mainboard series. Some of the power circuit elements are on the reverse side of the PCB. You can see a label there reporting that this product doesn’t contain lead and its compounds.

The PCB carries four GDDR3 memory chips from Hynix (HY5RS123235BFP-14, 16Mbx32, 1.8V). These chips have a capacity of 512Mb and a 32-bit memory bus. Four of them make up a memory bank with a total capacity of 256 megabytes and a 128-bit bus, which is standard for the Radeon HD 2600 XT. The chips with the FP-14 suffix have a rated frequency of 700 (1400) MHz, and this is indeed the frequency they are clocked at by the card. The ATI Radeon HD 2600 XT GDDR4 comes with 1100 (2200) MHz memory, so the Gigabyte card has a reduced memory bandwidth, which is going to affect its performance at resolutions of 1600x1200 pixels and higher and with full-screen antialiasing. We’ll check this out in our tests shortly.

As opposed to the memory frequency, the graphics core frequency is not lowered. It is 800MHz. The core has a standard configuration with 120 ALUs grouped into 24 universal shader processors with 5 ALUs in each, 2 texture processors equivalent to 8 classic TMUs, and 1 raster processor (ATI Technologies calls it a render back-end) roughly equivalent to 4 ordinary ROPs. There are no disabled subunits in this core. A yellow thermoplastic material typical of Gigabyte products serves as the thermal interface between the GPU die and the cooler’s sole.

Unlike the reference ATI Radeon HD 2600 XT GDDR4 design, this PCB doesn’t have a seat for a VIVO chip. The card offers a classic selection of connectors: two DVI-I and one universal S-Video/YPbPr connector. The PCB wiring provides for the installation of a HDMI connector instead of the bottom DVI. The connectors support dual-link mode, so you can attach two monitors to the card and enable a display resolution of 2560x1600 pixels. As opposed to the ATI Radeon HD 2600 Pro, the Gigabyte GV-RX26T256H supports CrossFire technology and offers two standard CrossFire connectors. Like the external connectors, the CrossFire ones are protected with special caps – just a nice trifle for the user.