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Abit Siluro FX 5900 OTES - Getting acquainted
It's another Geforce FX 5900 graphics card here at UKGamer, and this time we look at the outrageous Abit Siluro FX 5900 OTES. What sets this card apart from the host of others we've tested is its cooling solution. The Geforce FX 5900 as we already found out is a capable video card, but due to pricing it simply wasn't a viable option compared to a Radeon 9800 PRO. We find out whether that has changed thanks to time and Abit's engineering prowess.

We've already talked in depth about the NV35 and it's feature set on two occasions so we'll skip going over the same ground. However something we haven't talked much about is the OTES or Outside Thermal Exhaust System that was first used by Abit and then revised (but incorrectly implemented) on the ill-fated FX 5800 Ultra. When it was first seen on Geforce 4 Ti4200 cards there were a few complaints, apart from the fact that it took up an extra PCI slot, but it was quiet, had style and also produced good results when overclocking.

Then when NVIDIA produced a version very similar to Abit (presumably under license as the OTES is a patented design) we were shown how not to do it. Here on the Siluro FX 5900 we see it correctly implemented by the guys that invented it, and we're happy to report that it's quiet, although not exactly silent.

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The Siluro FX 5900 comes in a large box that surprisingly isn't all that heavy. That's because there isn't a whole lot inside apart from the video card itself. On the front we have a clear picture of the card inside along with bullet points outlining the main features of the package. The back doesn't present much information about the card itself but a fair bit on the OTES cooling solution. You get the feeling that it is the OTES that Abit are hoping will sway consumers to purchasing the FX 5900 OTES over the numerous other FX 5900s on the market.

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Inside things are slightly different to the usual. Neatly packaged in three separate compartments, the central of which holds the video card itself. The left compartment has two CDs, a very stylish 4-pin pass-through power cable and two manuals. On the right we have the various video cables.

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Sporting a royal blue PCB contrasting sharply against the grey aluminium heatsink, the 5900 OTES is a large card. Make no mistake when considering a purchase, this card has a two-slot cooling solution that is, thankfully, quiet. Heatsinks are present on both the front and back of the processor. With this being a 128MB version, no RAM modules are present on the back and thus no cooling either. We were immediately drawn to the clear Perspex ducting that channels air from the central heatsink region completely out of the computer. The OTES cooling solution is a sight in any computer.

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The card itself is dominated by the cooling solution and on the front we see all the electronics packed densely where the oversized heatsink doesn't cover the PCB. The power connector is angled perpendicular to the PCB which means your power connector will have to bend around the PCB and the power connector itself to fit in the slot.

The OTES cooling system overshadows most of the electrical gubbins on the front, with the vast majority pushed to the edge of the board. The size of the heatsink is something that strikes you after the initial snakeskin-esque ducting that funnels out the hot air.

The ducting can be taken off, although this still won't result in a single slot cooling solution. Efficiency of this ducting is uncertain, as its design allows for gaps where the air can escape back into the case. These gaps Abit say, allow the pressure inside the ducting to be kept low, although it's questionable how pressure can rise in such an open system?

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Through a rectangular cut-out in the backplane, the clear Perspex ducting exhausts the hot air. During operation should you place your hand in front of the exhaust, you can feel the warm air gushing through your fingertips.

Another interesting caveat is the ability to slide the fan, albeit less than a centimetre, along the 'rails' of the heatsink. The fan unit cannot be lifted off it's mount, but this allows for slightly better positioning and makes the retractable ducting taut. Four blue LEDS are positioned on the fan's small green PCB providing ample light. To further add mystique and the general aura of being different, the fan's blades are angled nearer the vertical, resulting in a greater volume of air being moved. Abit says that this also reduces turbulence.

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The heatsink unit is well finished for the most part, however there are points where the angular edges have been cut very roughly. For something that has been presented in such a polished manner in packaging and design, we were more than a little surprised to see this slip-up in standards. Another surprise is the use of aluminium as opposed to copper for the heatsink. Nevertheless, the OTES cooling unit is mighty impressive and has many nice touches. It's quiet and while we never really recommend two-slot cooling solutions, if you are forced to go down this route (as many 5900s are), then this is one of the best we've seen.

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The back of the card sticks to the more conservative design rules, with little out of the ordinary. The large aluminium heatsink provides further cooling around the NV35 processing unit, but during operation didn't get very hot itself. Its size also shouldn't cause worry as it's thin enough not to encroach on motherboard chipset coolers.


We couldn't do a review of an Abit product and not overclock it. As we found before, the Geforce FX 5900 can overclock pretty well although it would be wrong to say that every card overclocks like the one we have in our test bench, but it's always interesting to see how it performs when put under the kosh. What makes it even more interesting this time around is the less than standard cooling solution that is present.

So does the OTES make any difference?

Factory settings - NV35 GPU : 400MHz | RAM : 425MHz (850MHz DDR)
Through overclocking (no extra cooling or use of special BIOS) - NV35 GPU : 480MHz | RAM : 467.5MHz (935MHz DDR)

A very respectable overclock with only the Gainward 5900 doing better, albeit through cherry picking all their components. The interesting thing is when overclocked, most FX 5900s run at 5900 Ultra frequencies, but does this mean they perform equally? Lets find out.