by Oleg Golubovich
09/25/2006 | 05:30 PM
Products on the Nvidia GeForce 7600 GT chip haven’t been long on the market, yet have already gained recognition among people who appreciate inexpensive but fast graphics cards. The era of various versions of the 6600 GT has come to an end. Not that the 6600 GT is obsolete now, it is going to do its job well in a lot of computers worldwide, but it’s now time to meet the new best buy from Nvidia. The 7600 GT is an excellent product as is testified by numerous reviews. The manufacturer’s price policy also contributes to the growing popularity of graphics cards of that class. Anyone who keeps up with the computer market has to agree that we’ve got the success story of the 6600 GT repeated once again: high performance for the current generation of graphics hardware, low power consumption (in comparison with ATI’s competing offers), superb quality and affordable price. These factors can’t fail to make the 7600 GT a hit of the season.
<%BANNER[article]%>However, there is no end to perfection when it comes to graphics hardware. Overclockers everywhere are trying to improve upon the original manufacturer’s design by lifting the frequencies up, improving the cooling, modifying the power circuitry, and overclocking some more to reach new performance heights. This review is going to contribute to this process by covering the volt-modding of 7600 GT graphics cards that have the reference design.
We’ve got an e-GeForce 7600GT CO Superclocked graphics card from EVGA. It follows the reference design (Type P456) but has higher frequencies than the ordinary 7600 GT: 600/1580MHz instead of 560/1400MHz.
Take note that this review doesn’t cover quite a few of GeForce 7600 GT based cards due to differences in the PCB wiring, particularly the non-reference models offered by Gainward, MSI and Palit. So, before you try to modify your card, make sure it complies with Nvidia’s reference design. Then read our disclaimer and think again if you do really need that.
The modifications described in this article have been successfully made in practice. Each mod was tested by us and helped to achieve the desired result. We don’t accept any claims concerning damage to your graphics card or any other PC component after the modification – such problems imply your own mistakes. The author and X-bit Labs are not responsible for any damage inflicted by repeating anything of what is described in this article. We also cannot promise you that your final result will be as good as ours due to the variation in the potential of particular samples of graphics cards.
Warning! Volt-modding, if recognized, makes all warranty obligations void. So you should do everything neatly to be able to unsolder all back again in case of the device’s death.
You should take up volt-modding if all the following items are true:
Before doing any volt-modding, make sure the graphics card is properly cooled (the standard cooler may turn to be insufficient even for ordinary overclocking).
So, you’ve made up your mind? Let’s move on then. In order to experiment with a 7600 GT, you need:
The three last items can be replaced with an ordinary lead pencil, but we don’t use it often due to certain drawbacks. The lead from the pencil may crumble, so such a modification isn’t long-lasting. Moreover, you have to be very careful when “drawing” a resistance, and there’s a bigger risk of putting your graphics card to death than at ordinary volt modding. On the other hand, you can quickly remove all the modifications from your card.
So, it’s up to you to choose the particular tools. We are going to tell you how to use them.
The regulators we are interested in are located on the reverse side of the PCB:
By default, the core voltage on the 7600 GT card is about 1.3V in 2D mode and grows up a little (to 1.35V) in 3D mode. It is controlled by a P548DD4 regulator. To increase that voltage, you need to solder a 10,000Ohm variable resistor in parallel to the resistor marked in the photograph:
Make sure you’ve set the variable resistor at its maximum resistance before doing that!
The resistance of the resistor on the graphics card is initially set at 410-415 Ohms. You can now reduce it in steps of 30 Ohms to increase the voltage in steps of 0.1V.
The voltage read point is marked in the picture above.
You can do the same with a lead pencil by drawing over the marked resistor until you get the necessary resistance. The resistance must be immediately measured with a multimeter. Do not check the voltage out after you turn the graphics card on!
Memory power is controlled by yet another P548DD4 regulator. By default, the memory voltage is about 2.0V. To increase it, you need to add a variable resistor or draw over the marked resistor with a lead pencil as shown in the photograph:
You can increase the memory voltage with a step of 0.1V by reducing that resistance with a step of 25 Ohms.
The value of the memory voltage can be read from the point which is marked on the PCB as TP502 and is indicated in the picture above.
Like with the GPU volt-mod, you can do the same with a lead pencil: draw over the mentioned resistor, checking out the resulting resistance.
Before offering you the results of our tests, we have to warn you that you may not be exactly as lucky as we were. Your overclocking may be better or worse depending on the particular sample of the graphics card and the conditions you use it under.
We benchmarked the overclocked card on the following testbed:
Processor: AMD Sempron 3000+ (Palermo) Socket 939
Mainboard: ASRock 939DUAL-SATA2 (ULi1695+ULi1567)
Cooling: liquid cooling system (Asetek WaterChill Antarctica water-block on the CPU; Revoltec X-Freezer Rev.2 water-block on the GPU; Eheim 1048 pump; Airplex EVO 360 radiator cooled by a single 120mm Foxconn fan)
Memory: 2x512MB TwinMOS (Winbond UTT CH-5, -AA4T)
Power supply: 600W be quiet! Dark Power ATX 2.2
Hard drive: 120GB ATA-100 Hitachi (7200rpm)
Optical drives: TSST SH-D162C DVD-ROM and NEC ND-3520A DVD-RW
The CPU was working at a clock rate of 2840MHz (355x8) and at 1.6V voltage; the memory modules were working at 237MHz with 2-2-2-5 timings and 3.25V voltage.
We overclocked the card in Windows XP Professional SP1 by means of RivaTuner 2.0 RC16. The GPU was cooled by the water-block. We also installed a 120mm fan to blow at the reverse side of the PCB; it worked at its maximum speed.
The GPU voltage was increased to 1.65V, i.e. by 22%. The memory voltage was increased to 2.2V or 20% above the default value. As a result, we managed to overclock our card to an impressive 780/1880MHz! Before the volt-mod, the graphics card would only work at 650/1680MHz with its default cooler. To remind you, EVGA pre-overclocks that card to 600/1580MHz whereas the frequencies of the reference sample are 560/1400MHz.
To find out the practical worth of our overclocking, we benchmarked the card in 3DMark03 v.360 and 3DMark05 build 120 at their default settings. The graphics driver’s settings were an optimal compromise between quality and performance. Here are the results:
As might have been expected, the volt modification has helped raise the overclockability of the 7600 GT to a new level. The card’s performance has increased greatly as the consequence. This performance growth won’t be superfluous for those who dare to make a long-time volt-mod because it is 10-15% higher than what you can get from the card by means of ordinary overclocking.
If you do want to use your graphics card overclocked for long, do not increase the voltages too high, take care about proper cooling, and leave a dozen megahertz as a safety margin to avoid possible troubles.
So, many more megahertz and good samples of graphics cards to you!