Gigabyte’s original GA-P55-UD6 (reviewed December 2009) held the distinction of not only being the first board we tested with Intel’s LGA1156 socket, but also our preferred go-to board for months on end. It was only after Asus’s beautiful Maximus III Formula showed up in our March issue that the GA-P55-UD6 was dethroned.
It didn’t take Gigabyte long to fire a shot back, though, with its GA-P55A-UD6 board. At first glance, you’d think there was no difference between it and its predecessor. But up close, you can see slight changes to the board that make room for USB 3.0 and SATA 6 chips, as well as a slight repositioning of the PCB-mounted reset button. The most obvious physical change is the reduction in the number of inboard SATA ports. The GA-P55-UD6 had 10 ports whereas the GA-P55A-UD6 has eight. Both boards have two eSATA ports, compliments of a JMicron JMB362 part.
Nearly identical to the much-beloved GA-P55-UD6, the "A" version brings next-gen I/O to the table.
The reduction in SATA ports is likely due to the Marvell 88SE9128 SATA 6 controller’s support of just two ports. The 88SE9128 supports both IDE and AHCI modes, as well as a two-drive array RAID 0 and RAID 1.
Our major concern with the GA-P55A-UD6 isn’t really the fault of Gigabyte, but rather Intel. The P55 chipset doesn’t come with enough PCI Express lanes for a true enthusiast platform. If you remember, with LGA1156, PCI-E is moved into the CPU. That gives you 16 PCI-E 2.0 lanes, which operate as either a single x16 for one GPU or as two x8 for two GPUs. The P55’s PCH controller has another eight x1 PCI-E 2.0 lanes. However, according to Intel’s data sheets, they operate at 2.5GT/s, not the 5GT/s we’ve come to expect of real PCI-E 2.0 ports. That didn’t matter as much before USB 3.0 and SATA 6 came along, but a typical P55 board today will be starved for data.
For example, with two EVGA GeForce GTX 280 cards installed, the board’s SATA controller maxed out 165MB/s in HDTach. When one of the GPUs was removed, the board gave us SATA 6 burst speeds of 283MB/s. Want more proof there’s not enough PCI-E bandwidth? Manually setting the board’s third PCI-E slot to x4 mode would disable the board’s two other x1 PCI-E lanes. Sigh.
For those who don’t intend to fully load up a rig with multiple GPUs, a P55-based GA-P55A-UD6 is a fine board. You get all the things we loved about the original plus USB 3.0 speed and SATA 6—and hell, it’s still the only P55 board with six DIMM slots (although, you can’t run double-sided DIMMs in all, so be aware.)
But if you really want to build up a system with enough hardware that you can barely move your PC, you should opt for an X58-based board, where there are enough PCI-E lanes to choke on. Because let’s face it, when you’re shelling out $250 on a board like the GA-P55A-UD6, it’s going to be hard not to want a “real” board using X58 instead.
USB 3.0 and SATA 6; packed with features.
Too few PCI-E lanes to support a fully loaded system.
Asus Maximus III Formula
PCMark Vantage 64-bit Overall
Everest Ultimate 5.30.1900 Mem Read (MB/s)
Everest Ultimate 5.30.1900 Mem Write (MB/s)
Everest Ultimate 5.30.1900 Mem Copy (MB/s)
Everest Ultimate 5.30.1900 Mem Latency (ns)
SiSoft Sandra RAM Bandwidth (GB/s)
3DMark Vantage Overall
3DMark Vantage GPU
3DMark Vantage CPU
Valve Particle test (fps)
Resident Evil 5 low-res (fps)
World in Conflict low-res (fps)
World in Conflict (fps)
Best scores are bolded. For our tests we used a 2.93GHz Core i7-870, 8GB of Corsair DDR3/1333, a 150GB WD Raptor, an EVGA GeForce GTX 280, a PC Power and Cooling Turbo Cool 1200, and 64-bit Windows 7 Professional. For SATA 6 compliance, we used a Seagate Barracuda XT SATA 6 drive, and for USB 3.0 compliance, we used a Western Digital MyBook USB 3.0 drive.