Gigabyte P55M-UD4 review

Intel's Lynnfield Core i5 and Core i7 processors use the new LGA1156 socket, so we wouldn't have been able to test the Core i5-750 (opposite) without a compatible motherboard.

Thankfully, manufacturers were quick to provide us with samples, and this microATX board from Gigabyte had the lowest price.

The P55M-UD4 uses Intel's new P55 Express chipset, which is very different to the X58 chipset for the original Core i7 chips. The P55 doesn't have the usual Northbridge and Southbridge chips. The Northbridge functions are instead integrated into the Core i5 processor.

Unlike the Core 2 series, Core i5 and Core i7 chips have a built-in memory controller. This supports DDR3 memory only, which is a little faster than DDR2 modules but costs more too. If you're upgrading from a DDR2-based system, you'll need to factor in the extra cost. There's support for the usual dual-channel configurations, so P55 boards have four memory slots rather than the six found on the triple-channel X58 boards.

The processor has direct control over the two large PCI Express slots. You can run one slot at x16 speed, or two graphics cards at x8 each. Even at x8 speeds you won't max out the available bandwidth with any current graphics card, and there's support for both Nvidia's SLI and ATI's CrossFire standards.

Unlike most microATX boards, the P55M-UD4 has no onboard graphics or monitor outputs, and there's unlikely to be a variant of P55 with such features. Intel's next chip, codenamed Clarksfield and due later this year, will have integrated graphics. This hybrid CPU/GPU will require a special chipset, and the combination will replace traditional onboard graphics in Intel PCs. If you want to build a Core i5 PC today, you'll need a PCI Express graphics card, which will increase the overall cost.

All P55 boards have a comparatively slow 2GB/s Direct Media Interface (DMI) connecting the processor to the Southbridge, but this is still more than sufficient. The Southbridge can control up to eight PCI Express lanes, but only one PCI Express x4 slot is supported on this board. There's also one PCI slot, so to add a third expansion card, you'll need to forego dual graphics cards.

The P55 chipset provides five internal SATA II ports and an eSATA port on the same RAID 0/1/5/10 controller. Gigabyte has added a second controller - with an IDE port and two more SATA II ports - with RAID 0 and 1 support. The rear of the board has 10 USB ports, FireWire, Gigabit Ethernet and a single PS/2 port. For audio there's coaxial and optical S/PDIFs plus an eight-channel analogue output with support for Dolby Home Theatre.

The BIOS has a comprehensive array of options for manual overclocking, or you can use Intel's own Turbo Boost technology. We had trouble with this on some motherboards, but it worked well here.

This is a well-equipped board, but we can't get over the idea of a microATX board without built-in graphics. After the high prices we were quoted for P55 Express boards, it was a relief to find one for £116 - although it's still twice as much as many AM2+ boards, and you need DDR3 memory and a graphics card. For comparison, Gigabyte's AM2+ GA-M720-US3 board costs just £45 including VAT. Even if Core i5 beats AMD's Phenom II X4 range for performance and price, we'll still need to see cheaper P55 motherboards.

Gigabyte's graphics-less microATX board may be an oddity, but it's currently the most attractive prospect for those keen to build a Core i5 PC. With a combined price of around £250, you can't build a PC this powerful for less. However, combine an AM2+ board with built-in graphics, some DDR2 and a Phenom II processor, and you'll get ample performance for far less cash.