Verdict: Great layout and voltage options, but it's a poor overclocker.
Not to be outdone by its CPU division, which appears to launch several new processors every month, Intel's chipset division has also jumped on the 'let's launch so many products that AMD won't stand a chance' bandwagon. The end result is the X48 chipset, which we first saw last month on the turbocharged but ludicrously expensive Asus P5E3 Premium WiFi-AP.
The X48 chipset has support for two 16x PCI-E 2.0 slots, which could be used to CrossFire two ATI graphics cards. However, there's no SLI support - for that, you'll need to buy an Intel D5400XS Skulltrail motherboard or an Nvidia chipset board. In fact, the only difference between the X48 and the X38 chipsets is the former's official support for 400MHz FSB (1,600MHz effective) CPUs. However, most X38 motherboards we've tested can easily run a 500MHz (2GHz effective) FSB when overclocked.
The GA-X48-DQ6 could be used as a textbook example of good PCB design for other manufacturers to follow. The two high-speed PCI-E slots are spaced well apart from each other, leaving plenty of room for large graphics coolers. The power and I/O sockets are located on the outer edges of the PCB, while the EIDE port has been mounted parallel with the board to facilitate tidy cabling.
In addition to the two PCI-E graphics slots, there are three 1x PCI-E slots, plus a pair of PCI slots.
The Northbridge, Southbridge and VRM heatsinks are composed of copper and linked by several heatpipes. It's a neat and tidy design, and doesn't get in the way when mounting a large CPU cooler. There's also a huge chunk of copper called 'CrazyCool' on the underside of the board, although we're sceptical about whether this provides any major benefit.
The GA-X48-DQ6 couldn't be a premium Gigabyte motherboard if it didn't have more I/O ports than necessary. It has eight S-ATA II ports, 12 USB 2 ports, three FireWire ports (one is mini-FireWire), plus coaxial and digital S/PDIF outputs for its Intel HD Audio-compatible on-board sound chip. You'll always have somewhere to plug in your latest gadget, but none of this comes for free.
Although Intel markets the X48 chipset as a high-end chipset, the GA-X48-DQ6 only supports DDR2. The GA-X48T-DQ6 (note the 'T' in the middle) is the DDR3 version, and worth investigating if you fancy pushing overall system performance even further. While DDR2 keeps costs down, X48 is targeted at high-end users, for which DDR3 is more suited.
Once updated with the latest BIOS (revision F5), we ran the GA-X48-DQ6 through our standard suite of tests. It achieved an overall score of 953 in our Media Benchmarks, which is respectable but easily exceeded by other DDR2 motherboards, such as the P35-based Asus P5K Premium WiFi-AP - the current king of motherboards.
The BIOS provides a reasonable degree of control when overclocking, although Gigabyte insists on displaying only the increments of voltage increase (+0.2V, for example), rather than absolute values, which are easier to work from. If you're feeling brave, and have plenty of LN2 to spare, you can send up to 2.35V through the CPU. However, if your CPU is air cooled, we wouldn't recommend increasing the vcore of a Core 2 CPU beyond 1.6V, unless you like the smell of burnt silicon. The RAM voltage can be increased by 1.55V, again more than is ever likely to be necessary, while the FSB and Northbridge voltages can be boosted by 0.35V and 0.375V respectively. More advanced voltage controls include GTL and the PCI-E bus, although there's no PLL control.
As we expected, the GA-X48-DQ6 easily managed to max out our test CPU, a 2.66GHz Core 2 Duo E6750, by overclocking it to its maximum 3.66GHz with a 458MHz FSB (1,832MHz effective). At this setting, the GA-X48-DQ6 was a little slow, with an overall score of 1,225 compared to the 1,307 of the Asus P5K board. Despite maxing out the FSB and Northbridge voltages, the GA-X48-DQ6 wouldn't run stably with the FSB any higher than 500MHz, which is a poor showing for an X48 motherboard. For example, the Asus X48 board was able to benchmark stably with a 535MHz FSB.
Conclusion
An X48 motherboard is all about speed and extreme overclocking, and these are precisely the two qualities that the GA-X48-DQ6 fails to deliver. Out of the box, the GA-X48-DQ6 produces only average performance, which even overclocking can't correct. Given that it can't be overclocked as far as other X38 and X48 motherboards, the GA-X48-DQ6 is best avoided, despite the obvious effort that Gigabyte has put into the excellent PCB design, and the array of voltage options in the BIOS.
