8800GT Overclocking with Voltage Mod

Well, after my power consumption check in one of my earlier post, I'm very much keen to go back to pushing my PC's limits since I know it's not the main culprit of my high electricity bill hehe.

Since the beginning, I've pretty much concentrated on overclocking the CPU. I felt more comfortable doing that because I know I have more than adequate cooling on it with the Swiftech water cooling setup. I was getting about 32C with air-conditioning and about 38C at room temp which was very very good in my perspective. The first processor I got from Intel and into this system was the QX6700 (Kentsfield). I was able to push it to about 3.6Ghz from its stock 2.66Ghz. That was using nearly 1.45V and temps was reaching 45C at idle. I really want to hit that sweet 4Ghz spot.

QX9650, 45nm Yorkfield

I have since swapped the Kentsfield for a newer QX9650 (Yorkfield 2.93Ghz) processor. Using FSB overclocking, the highest I got was 3.9Ghz. The moment I tried 400Mhz FSB or higher, the BIOS just would not boot and it will default all settings back. I checked around in the forums and found out that my board, the Foxconn X38A, had significant FSB hole issues which varies from customer to customer. For my case, the hole was at 400Mhz. I do not know if there are any passing regions above 400Mhz bsince I did not try pushing blindly passed it. Foxconn has also appeared to have stopped updating the BIOS for this board to improve on overclocking (I'm never buying Foxconn again) So I went with multiplier overclocking instead. Using the mobo's recommended voltage setting based on the multiplier number you chosed, it took me only 10 minutes to climb from a ratio 9 to a ratio 12 effectively bringing me to 4.0Ghz. Voltage required was a low 1.375V :)

Anyways, back to what I really want to talk about, my graphic card overclocking experience! The Galaxy 8800GT that I own ships with all it's clocks at default NVidia stock settings: 600Mhz Core/1500Mhz Shaders/900Mhz Memory. My original card was defective after a few weeks (would not show BIOS but ok in Windows) and I got it replaced while under warranty. At that time, Galaxy had already revised it's 8800GT lineup and offered it in two new configurations; one with a Zalman copper heatsink and the other with a dual slot covered cooling. Both had 2 6pin connectors at the back instead of the regular 1 for all 8800GTs which Galaxy said is supposed to improve voltage stability for overclocking (cool!). Here are the cards:

The dual slot cooling version

The Zalman spiral copper heatsink version

What I ended up getting was the two slot full cover version. Though I was pretty pissed since the Zalman version looks much cooler and probably cools way better anyway but I soon had a change of mind. Remember when I said that these cards gave you option to connect two 6-pin power from your PSU? Here is why: The card comes with its on 3-phase voltage mod jumper! By changing the position of the jumper from it's two positions or removing it totally, you get to decide 3 different core voltage the card will be getting. Good news since no more solder gun or wires needed to volt-mod this card.

Observe the yellow colored jumper located at the end of the card next to the dual 6-pin connectors.

However, I did not try the jumpers partly due to worries of total system consumption but not anymore haha. However, found out that Rivatuner, the popular tool for Nvidia & ATI GPU overclocking, is not able to recognize the drivers I have installed. Though I was able to force it to recognize the driver version, I just won't be able to trust the overclocking done by it. So, looked around and found another cool tool to get the job done. Introducing, EVGA Precision software. Too bad it only works for NVidia cards.

EVGA Precision

Armed with 3DMarkVantage, here are the overclocking results. I slowly increased the core clocks with increments of 10Mhz each with shaders unlinked. I did not hit any issues midway and stopped at a healthy 685/1680/950 configuration for my first benchmark.

Do note that at stock clocks, the 8800GT gives about 5,200+ GPU scores. Here we are seeing a 5,552 GPU score. A nice 6.7% increase. Also, the test completed without any errors or freezes indicating the card is still stable. Temps measured during benchmark (thanks to EVGA Precision's added feature to display on-screen real-time GPU temps) was steady at 70C. Stock cooler is holding on it seems haha

Let us continue. Next stop: 690/1680/960 (increase in core and memory clocks)

Did not see much increase in with a 5,571 score so time to take a more aggressive approach. I linked the shaders to the core and increased the memory clocks to hit a nice 1000Mhz(Galaxy uses higher rated Samsung chips known to hit 1100Mhz which can perform better compared to the usual Qimonda memory). Benched at 700/1750/1000 clocks:

Now we're talking. GPU scores have hit 5,792 here. Thats a full 500+ points increase over stock values. For the final bench, I increased the core clocks another 10Mhz for a final configuration of 710/1775/1000 and Oced my CPU back to 4Ghz (I went back to default temporarily for the power consumption analysis). This is where my PC currently stands:

In summary, I've managed to squeeze an extra 13.15% of performance from my card with the voltage mod (Final GPU score of 5,884 vs stock's 5,200). I know my card cannot hit 700Mhz without problems when I tried last time and that has been solved with higher voltage provided to the chip. However, the card temps are now hovering dangerously near the 80C limit I set for myself (I just don't like to see high temps on any of my parts) and started to show artifacts on ATITool around that temp. However, if I were to water-cool the card or perhaps get the Accelero cooler, I could actually push the clocks even higher :)

Anyways, that's news for another day. For now, I'm just gonna enjoy my extra graphics boosts with some games (let me see how much better frames I get in Crysis hehe). Some closing pics showing improved Windows rating before/after OC. Bye guys!

Graphic score of 5.9 before OC

Graphic score of 6.1 after OC