Report: Overclocking with OpenBIOS (1/1)

As our more frequent readers will recall, we published a comparison of two GeForce2 GTS Deluxe cards a short while back (see the review here). The review was also meant to include some overclocking tests. Unfortunately the AOpen PA 256 Deluxe, a card that seems perfect for overclocking courtesy of its OpenBIOS, was unable to complete these tests due to a faulty fan on our review board. The fan only ran at half the specified speed, so the OpenBIOS GPU monitoring and overclocking utility kept displaying warning messages.

OpenBios menu

While the cooling produced by the lower fan speed was still barely sufficient for normal operation, there wasn't enough headroom to allow for overclocking without frying the chip. Now AOpen has sent us a second board, this time with a fully operational fan. So, we are now able to present you with the results of our experiment in overclocking using the OpenBIOS.

The OpenBIOS is re-programmable bios, similar to those found on mainboards. To get into the OpenBIOS, just press [INS] during boot up, and you'll get into a menu which lets you set and change various of the board's operating parameters. The most important of these are the chip and memory speed, AGP mode (1x, 2x, 4x,), and sidebanding, as well as support for fast writes. So far, AOpen is the only video card manufacturer to offer this kind of feature in a mainstream board.

It seems that the card already runs with increased voltage in standard mode. At least that's what the Windows software reported: Core 2,11V (2,05V); V-Core 1,31V (1,25V); Memory 2,52V (2,50V). The first set of numbers represents the actual setting on the AOpen board, while those in parantheses are the default settings per NVIDIA's specification and the values set in the bios menu.

Using these default settings, the card runs at speeds as high as 200 / 412 MHz, a good 23% above the stock memory speed, without needing a further increase in voltage. This is an extraordinarily high increase for a standard 32MB GTS card using memory rated at 6ns. Many other 32MB GTS have great trouble reaching even 370 MHz. At any rate, these settings are the definite ceiling for this card: I was able to get about two benchmark runs out of the board before it would freeze up or crash my system. I was expecting to get a few more MHz out of the card by raising the voltage just a tad more, just as you would with a CPU, but I was out of luck. Higher voltage means more heat, which in return requires better cooling. I'm positive you could eke just a bit more out of this card, provided you're willing to invest into a good cooling solution.

OpenGPU, AOpen's overclocking utility, monitors all important board parameters like chip temperature, voltages and fan speed. You can change voltages and operating frequencies from within Windows. Temperatures of around 50° C are a critical point for overclocking.

Nowadays, increasing the chip's frequency doesn't do all that much for performance anyway. Usually it's the memory that turns out to be the limiting factor, regardless of how fast the GPU is running. Besides, there isn't a game today that requires more polygons than a GeForce2 GTS running at 200MHz is able to render, not even those that allready support hardware T&L. Increased voltage just increases the chip's and the memory's heat dissipation, and since the clock generator is integrated into the chip itself, you might create more problems for yourself by overclocking the core.

Voltage: Even though increasing the voltage by one step doesn't allow you to run the card much faster than at the standard voltage, it does lead to a noticeable increase in operating stability at the same (overclocked) frequency. After all, a stable system that doesn't lock up on you in the middle of a deathmatch is more important than a marginal 5MHz increase in speed. What good is your overclocked hot-rod of a card if it'll quit on you after 5 minutes? A room that is just a few degrees warmer than your usual surroundings can push a seemingly stable card over the edge...

Thanks to OpenBIOS and the voltage tweaks it allows, I was able to run this card stable at the 200 / 400 MHz setting during everyday use and testing (But don´t ask me how lonk the card lasts...). So the OpenBIOS gives you an overclocking advantage, even though it turns out to be a bit smaller than expected in terms of peak clock. Still, that might very well just be because the card already ships slightly "tweaked".

AOpen Homepage

10.11.2000 by Lars "Borsti" Weinand

Translation by Benjamin Kraft

Copyright: 10.11.2000 -   RIVA Station 2000 - Lars Weinand
No Copy without Permission!

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