MSI's P55M-GD45 motherboard
Black and blue and, er, MicroATX

Unlike Gigabyte, MSI has just one MicroATX motherboard in its P55 lineup: the P55M-GD45. At close to $125 online, the GD45 costs about $20 less than the UD4. So what do you lose? SLI, for one. Although AMD supports CrossFire on just about every P55-based motherboard with a pair of physical x16 slots, Nvidia requires that individual models be SLI-certified. The GD45 will happily accommodate a couple of GeForce graphics cards as long as one is dedicated to PhysX processing, but you can't team the pair to share the pixel-processing workload.

Of course, given the performance of AMD's latest Radeons, SLI support is something most folks can probably do without. You can build a heck of a gaming system with just a single graphics card and still be confident that the latest titles will run fluidly at resolutions up to 2560x1600.

At first glance, the GD45 looks very much like the sort of board you might put inside a fancy gaming rig. The black-and-blue color scheme has a menacing edge, and I quite like the pewter tone of the chipset and voltage circuitry heatsinks.

The VRM cooler is tiny compared to what we're used to seeing on enthusiast-oriented motherboards, but I've often wondered whether massive clumps of copper linked by intricate heatpipe arrays were really necessary. Granted, the GD45 has only four power phases supplying the processor—one third the number available on the Gigabyte board. MSI claims that just one of its so-called DrMOS MOSFETs is better than four "traditional" ones, although Asus and Gigabyte both argue that their boards use higher-quality MOSFETs than what would presumably be classified as "traditional" designs. Comparing CPU power implementations from different manufacturers is more complicated than counting phases, but it is worth noting that the GD45 has two fewer phases than MSI's mid-range P55-GD65 ATX model.

In addition to purportedly higher-quality MOSFETs, the GD45 uses solid-state capacitors throughout. The board has four layers, just like the UD4, but its copper layer contains just a single ounce of the conductive stuff. One-ounce copper layers are still the industry standard. Although Asus and Gigabyte claim that two-ounce layers lower board-level impedance, we've yet to see that translate into tangible benefits for end users.

MSI eschews auxiliary storage controllers for the GD45's internal SATA connectivity, instead relying on the six 3Gbps ports provided by the P55 chipset. As on the Gigabyte board, the edge-mounted ports leave plenty of clearance for longer graphics cards, but they could present problems in tighter enclosures that put hard drive cages or other obstructions right next to the motherboard tray. In fact, the GD45's SATA ports are even closer to the edge than on the UD4.

Speaking of clearance issues, I should note that the DIMM slot tabs on both the UD4 and GD45 snug right up next to longer PCI Express graphics cards. This placement can make swapping memory modules difficult when a graphics card is installed, although that's not the sort of thing most folks would do with any regularity. A little layout crowding is inescapable given the dimensional constraints presented by the MicroATX standard.

The GD45's lack of SLI certification probably stems from the arrangement of electrical lanes connected to its physical x16 slots. All 16 of the PCI Express 2.0 lanes found in Lynnfield CPUs flow to the first slot, while the second must make do with four lanes of connectivity from the P55 chipset. Worse yet, the P55's PCIe lanes only signal at 2.5 GT/s, which is the same speed as a first-generation PCI Express. Effectively, you're looking at a x16/x2 configuration for dual graphics cards. That config doesn't make the cut for SLI certification, and it may not be ideal for CrossFire, either.

A whopping ten USB ports adorn the GD45's port cluster. Unfortunately, none of them are cross-bred with the board's dual eSATA ports. I'd happily trade both non-powered eSATA ports for just one hybrid eSATA/USB connector.

Although the port cluster looks otherwise stacked, a digital S/PDIF audio output is conspicuously missing. There's an S/PDIF header on the board, and the manual makes mention of an optional PCI back plate connector with an RCA output, but that part doesn't seem to be included with any of the GD45s currently available at online retailers.

Realtek's ALC889 codec handles the silicon side of the audio equation, but unlike the ALC889A on the Gigabyte board, real-time Dolby Digital Live encoding isn't supported. This limitation should only affect gamers looking to output multi-channel audio over a digital connection, since the ALC889 is still capable of passing pre-encoded audio tracks, such as those found with movies, over S/PDIF.

Although the MSI and Gigabyte BIOSes differ a little in their presentation and the specific ranges and granularity available with various overclocking and tweaking options, enthusiasts engaged in the usual performance tuning should find them functionally equivalent. Fan speed controls are the obvious exception, and MSI deserves props for allowing users not only to set a target CPU temperature between 40 and 70°C in 5° increments, but also to choose a minimum fan speed between 0 and 87.5% in 12.5% increments. Even though temperature-based fan speed control isn't available for the board's two system fan headers, each can be set to run at 50, 75, or 100% of full speed.