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ATI's Radeon X850 XT Platinum Edition Preview

by Ryszard Sommefeldt on 30 November 2004, 00:00

Tags: ATi Technologies (NYSE:AMD)

Quick Link: HEXUS.net/qa5i

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Reference Board Examination

Since R480 is functionally identical at a GPU level to R423 and R420, if you want to see how fast an AGP X800 XT Platinum Edition goes, for a yard stick, click here.

In terms of the physical manifestation though, X850 XT Platinum Edition is a little more different, compared to the product it's replacing.

X850 Platinum Edition

X850 Platinum Edition Rear

X850 Platinum Edition Rear

Cooler from the intake section

Side on from the back

Side on from the PCI Express slot

As you can see, the X850 XT Platinum Edition is clad in a dual-slot cooler with rotary blower installed, pulling air from inside the case and through the copper heatsink, before ejecting it from the case through the vents on the backplane. That the air is pulled through the cooler is telling, since you can see in the picture that the heatsink has an array of 44 skived fins, fins that are part of the original copper block.

For want of easier words, the fins are 'pulled' away from the copper block (think of a knife slicing into cheese and that 'flap' of cheese being lifted up into a fin), meaning there's never a solder or brazed point where the fins are attached, which can create thermal problems (and extra mass). Skiving means the engineer(s) who designed the heatsink for ATI avoid that problem. Notice also that the plastic shroud that dictates airflow out through the backplane isn't as wide as the backplane itself. That suggests that maybe ATI trialled other designs that were as wide, but settled on the current design after consideration.

The memory modules, Samsung's GC16 GDDR3 devices - rated to 1200MHz - are active cooled on the top side by the heatsink and fan assembly. The heatsink is held on by a number of retaining screws and is simple to remove. The memory modules on the rear of the board are cooled passively by an L-shaped aluminium plate that also holds the heatsink assembly to the front of the card.

Being a high-end PCI Express graphics card, the X850 XT PE needs extra help in the power department, ATI bestowing the board with the same 6-pin connector as we've seen recently on a bunch of similar hardware.


Naked, you can see the large die.

R480 Core

The cooler assembly is a three piece affair, consisting of the cooler on top, the retention plate underneath and the tension bar across the rear of the core.

The retention plate is a point of extreme interest. Look at the following picture.

Backplate resting

The retention plate is completely touching those two pairs of SMD parts underneath. It's debatable whether they're hindering the cooling performance of the DRAM devices that the plate is also helping to cool, but there's no denying that it's suboptimal in a couple of ways. The DRAM cooling is the first, the second is that I wouldn't imagine the SMD devices enjoy being compressed by the plate, as it isn't held to the card using spring-loaded screws for a 'correct' load, just brute force. However, I'm sure ATI have considered what's going on and have accounted for it internally, although it would be nice to hear their reasoning behind not making a couple of cut-out sections on that edge of the plate, to avoid the components.

Weighing in at a portly 460g, it's more than the weight of a pair of XFX 6600 GT PEG boards, some 120g heavier than a 6800 GT AGP reference board and 64g heavier than a 6800 Ultra AGP reference board. It actually tips the scales by 2g as the heaviest board I've weighed to date, beating an ASUS Radeon 9800 XT AGP.

Finally, dual DVI makes a welcome appearance on a high-end ATI product and I'd be very surprised to see it missed off of any retail examples.

Noise and heat

Despite fears that the cooler would be the next 'Dustbuster', it was actually no such thing for me. Fan speed is 100% at startup, dropping shortly after. From then on, after boot, it never got louder for me, even during extended benchmarking. And the noise that it does make is no more annoying or audible than the 6800 Ultra's reference cooler. I ran both of those boards back to back during testing and I couldn't tell the difference between either, except on bootup. Should your X850 XT Platinum Edition sport this reference cooler and should it have cause to spin its fan up to 100% while gaming or otherwise being worked hard, be prepared for an annoying, high-pitched, loud noise as the blower does its thing. That would give me cause to complain, but since it never happened during testing, it comes across as a well designed thermal solution for the board.

And while ATI have never done a dual-slot reference cooler before, so what? Yes, there's extreme irony in them doing so, given the pelters they aimed at NVIDIA upon 5800 Ultra's launch. But it's effective, it works well and it allowed the board to be cool (in terms of looks I mean, I quite like it) and somewhat quiet during testing.

But, and there's always a but, the heat given off by the card, especially on the back side of the board under heavy load, is tremendous. While the majority of the heat the card makes is pushed out the back of your case by the blower, large amounts are just dumped into the case from the back of the board. That heat rises, and guess what's right above the GPU in your usual ATX case? If your CPU is on the ragged edge in terms of thermals, you'll have to consider the extra heat an X850 XT Platinum Edition will drop into your system, which is certainly more than any other graphics card I've personally ever come across.