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Sapphire Radeon X1950 Pro 512Mb AGP:
Review and Testing

Paul V. Bolotoff
Release date: 31st of March 2007
Last modify date: 12th of December 2007


Cooling System

The radiator of this cooling system covers both the graphprocessor and all eight memory chips, though rubber pads are involved in the latter case. There are two power field-effect transistors (FETs) and one stabiliser chip cooled with help of this radiator. Of course, rubber pads have been used for them too.
Sapphire Radeon X1950 Pro 512Mb AGP (front view with the radiator removed)
(click to enlarge, 146Kb)

The radiator consists of two parts attached loosely to each other. The smaller is made of copper and serves for graphprocessor cooling while the larger aluminium one is supposed to service those memory and power chips. By the way, the copper part is well polished while the aluminium part doesn't seem to have experienced any improvements after casting. There are 32 aluminium ribs of variable length (from 32 mm to 118 mm and ˜0.3 mm thick each) which are soldered to the copper plate (˜1.3 mm thick). You can notice a rectangular hole in the aluminium part which is for Rage Theater cooling. Oh yes, it's supposed to be for this purpose, but the chip itself is missing. As a result, no video input capabilities. A fast 65 mm fan with 33 wings by ADDA (AD6512HB-TB3 0.40A 12V) is mounted on the aluminium part of the radiator and requires a regular 3-pin connector to draw power from. Air is blown along the radiator's ribs in the left direction, and that's strange a bit because there is no easy way for it to get outside of computer case. In general, this is a pretty much unusual design, though not much effective probably. All right, we'll see.
Sapphire Radeon X1950 Pro 512Mb AGP (the radiator's back)
(click to enlarge, 67Kb)
Sapphire Radeon X1950 Pro 512Mb AGP (the radiator exposed)
(click to enlarge, 83Kb)

Basic Components

As it has been mentioned previously, the card is based upon an ATI RV570 graphprocessor which is clocked at 580.50MHz. It comprises a whole lot of 330 mln. transistors and is manufactured using a 80 nm technological process by TSMC. This graphprocessor is somewhat simplified R580 which consists of 384 mln. transistors and is manufactured using a 90 nm technological process. It needs to mention that R580 is used for top performance ATI/AMD video cards such as X1900XTX/X1950XTX and X1900XT/X1950XT. The primary difference between R580 and RV570 is a reduced by 1/4 number of pixel and texture pipelines: 36 pixel and 12 texture (12 pixel and 4 texture per cluster subdivided for execution sets of 3 pixel and 1 texture pipeline each). The number of vertex pipelines remains unchanged if compared to R580 and there are 8 of them. Although the architecture of ATI pixel and vertex shader hardware hasn't changed from R300 to R580 with RV570 (until R600 which is of a totally different architecture featuring unified shader pipelines), let's make a brief review once again.
Every pixel pipeline consists of 3 execution units: a 32-bit floating-point scalar unit, a 96-bit vector unit called Vec3 (processes three 32-bit floating-point operands at once) and a branch execution unit for flow control code. Both scalar and vector units are 2-stage pipelined: the first stage (preparating) is for ADD instructions only while the second (primary) is for ADD\MUL\MADD instructions with texture access. One pixel pipeline processes one pixel per clock with up to either two 32-bit scalar operands or one 32-bit scalar + one 96-bit vector operand or just one 128-bit vector operand (considering a 32-bit scalar unit as an extension of a respective 96-bit vector unit). A vertex pipeline architecture is different somewhat and comes in a fashion of one 32-bit floating-point scalar unit + one 128-bit vector unit called Vec4 which processes four 32-bit floating-point operands at once. In addition, a texture pipeline consists of one addressing and one filtering unit as well as of a raster operator (ROP) to handle rasterising, blending, anti-aliasing and depth or stencil buffer related tasks.
In general, all 12 pixel pipelines of a single cluster are supposed to render consequently 4 batches of 12 pixels given the same shader code (12x4 mode). The pixel and vertex processing logic of RV570 complies with the Shader Model 3.0 (SM 3.0) specification even though there is no support for vertex texturing implemented as there in none in R580 though. There are no locked pipelines because cores with some defects are used for Radeon X1650XT cards under the name of RV560 with one cluster disabled (i.e. minus 12 pixel and 4 texture pipelines), and a 128-bit data bus to video memory is involved instead of a 256-bit one.
Sapphire Radeon X1950 Pro 512Mb AGP (RV570)

There is a PCIe to AGP bridge called RIALTO. This chip has been observed for the first time in AGP based video cards of Radeon X800 series, but seems to be useful still. It complies with the AGP 3.0 specification, hence supports data transfers at 8x of nominal bus speed with SBA (SideBand Addressing) and FW (Fast Write), thus delivering up to 2.1GB/s of bandwidth or even more with the AGP bus overclocking.
There are eight 512Mbit Hynix GDDR3 SDRAM 1.4ns (HY5RS123235 FP-14 — PDF datasheet, 816Kb) memory chips, and each one contains 8 banks x 2097152 32-bit words. So, there are 512Mb of video memory with a 256-bit data bus (eight 32-bit channels actually) just like in Radeon X1950XTX or X1950XT. These memory chips are clocked at 351.00MHz (1404.00MHz effective) what corresponds to their marking — 350MHz (1400MHz effective). Not a good news to overclockers probably.
It needs to mention that memory controllers of R520, R580 and RV570 are different significantly to those implemented in earlier designs. There is no cross-bar switch driving two or four memory channels but two identical 256-bit wide rings which transfer data in opposite directions. Both rings have four bus arbiters with hardware logic to drive two 32-bit channels. Effective data transfer path between two particular arbiters is between 1/4 to 1/2 of the ring length.
The graphprocessor stabiliser is based upon a Volterra 1165MF PWM controller (VT1165MF) which drives two channels, and every of them features a Volterra 1165SF (VT1165SF) power FET. In addition, there is a Volterra 223TF (VT223TF) chip to be held responsible for video memory power supply. Unfortunately, it's a bit problematical to be more descriptive here because there are no data sheets available on the Net. In theory, they may be obtained from Volterra directly after signing a NDA (Non-Disclosure Agreement), but that's strange very much because such agreements are supposed to protect intellectual property which has very little to do with basic capabilities of stabilisers and FETs. It can be stated only that this design runs VT1165SF FETs at clock speed of 1MHz, what makes a problem even in case of solid electrolytic capacitors. That's right, there are only two liquid electrolytic 100µF/16V capacitors of an unknown brand installed. Of course, they can handle some secondary tasks only. The primary load is imposed on 10µF multilayer ceramic capacitors (MLCCs) which have been installed in large quantity: 30 units to feed the RV570 and 10 units to help the memory.
In general, it must be said that the card's quality isn't high enough to correspond with the card's price. It seems like the manufacturer has been inclined to save as much as possible on the components. All right, there is no Rage Theater, not all capacitors have been installed, but why to save on a piezoelectrical buzzer? It's missing together with all driving chips, though their aggregate costs are miserable indeed. In addition, there are several design flaws like the following one which has been fixed by some Sapphire employee manually. For those unfamiliar with electronics, there is a conductor on the left of the RIALTO where a transistor is supposed to be. Oh yes, one more thing about this bridge chip: it gets very hot in run-time and deserves for some radiator at least, not that funky pinky protective rubber pad which complicates cooling even more, and that's why it has been removed.
Sapphire Radeon X1950 Pro 512Mb AGP (RIALTO and this fix)
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Copyright (c) Paul V. Bolotoff, 2006-07. All rights reserved.
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