Gigabyte EX58-Extreme is flexible

WHEN Core i7 975 was launched, it received rave reviews for its overclocking abilities on simple air cooling. Up to 4GHz is a given for pretty much every CPU and some can go even higher.

But up is not the only way. If you stick with the default speed - still a pretty fast 3.33GHz - you can wind down the voltage and save a lot of power.

Cranking up the speed is obviously what you'd do for intensive uses, like high-end gaming. Reducing power consumptiion is useful for having a greener office. In most cases, either mode can be selected from BIOS or Windows OC utility as a pre-set profile.

You need a darn good mainboard to make maximum use of this expensive chip, not just in terms of features and performance, but also power conversion. The two biggie Taiwan vendors, Asus and Gigabyte, have focused their efforts here to grab a share of early adopter money from power users, such as animation studios and engineering firms.

This is Gigabyte's EX58-Extreme, with possibly the most advanced chipset and VRM air cooling system around. It's other features include 10 SATA2 storage ports, compared to the usual six, dual Gigabit Ethernet, Virtual Dual BIOS, Dynamic Energy Saver, and, of course, Gigabyte's 2oz Copper trademark inner mainboard layers.


The Core i7 975 CPU is cooled by a modified Thermalright heatsink using a Thermaltake 2,700rpm fan. There are 6GB of Qimonda Aeneon Xtune DDR3-1866 memory and Gigabyte's GTX250 1GB OC graphics, all running off a Corsair 1000W PSU.

We tested the sustained high-end overclocking and low-power modes on these settings:

4GHz (133MHz x Multiplier 30) OC: CPU voltage at 1.375V; memory voltage at DDR3-1600 at 1.5V.

3.33GHz (133 MHz x Multiplier 25) default: CPU voltage at 1.10V; memory voltage at DDR3-1333 at 1.4V.

In both cases, the OS had to boot smoothly, and pass the usual Sandra endurance test.

Interestingly, the Gigabyte board also supports the upcoming low voltage 1.3V and 1.4V DDR3 memory, akin to what Geil and others showed at Computex. We've also reduced all the DDR3 reference clocks in proportion.

We got the following results:

Note the temperature results. While the BIOS monitor showed the CPU pretty much cooler than the outside air in the test room (in Singapore), Sandra showed a more realistic 39C in the Vista for the low power mode, and 47C for the 4GHz mode. These would still be usual when running high loads, but nevertheless, these are good numbers for reliable long-term running in either case.

The impact? In the 4GHz OC mode, yet with voltage not much higher than the CPU default, you get up to 20 per cent extra performance without dramatically increasing the system power.

Meanwhile, the low power option knocks 30 per cent off the CPU power consumption and over 10 per cent off the memory, without sacrificing any default performance. All this was done within a few hours, so more can be obtained from further BIOS tweaks.

In summary, the board performed well driving the Core i7 975 in either mode. It's overbuilt cooling may be of some help here too, keeping the test set-up reasonably cool even in a hot ambient environment.

To improve this further, Gigabyte should make the main waterblock modular for easier replacement, and use a message-based board status display rather than hex-code. µ