XFX's MD-A72P-7509 motherboard
The 750a in its element
Our first look at the nForce 750a SLI comes courtesy of XFX's MD-A72P-7509 motherboard. This board's goal seems to be channeling 750a's inherent goodness rather than wowing users with indulgent excess. XFX doesn't even resort to catching your eye with flashy board colorsclassic PCB green is back, baby. After the veritable rainbow of multicolored mobos that have paraded through the Benchmarking Sweatshop over the years, the retro look is a welcome change. However, unless you're running a case window, a motherboard's aesthetic appeal lasts only minutes before it's effectively shuttered from the world inside an enclosure that is ideally never to be opened again. So much for style.XFX pulls most of the board's functionality from the chipset, so we don't find much in the way of auxiliary ports, slots, and peripheral chips. This approach gives the board designers plenty of square footage to work with, resulting in a clean layout with few clearance problems.
We tend to be particularly picky about the placement of power plugs, and XFX does well to put the auxiliary 12V connection up along the top edge of the board where cabling won't interfere with airflow around the CPU socket. If you run an upside-down case like CoolerMaster's Cosmos 1000, though, you'll probably need an extension cable to reach the 12V plug. XFX keeps the primary power connector mid-way down the board, so cable reach shouldn't be a problem there.Power is routed to the CPU socket through four-phase circuitry that betrays the MD-A72P-7509's modest aspirations. The board is only rated for use with processors that have a thermal design power (TDP) up to 95W, leaving the Phenom X4 9850 and 9950 Black Edition CPUs that carry respective 125W and 140W TDPs off of the official compatibility list. XFX says the cost of supporting those power-hungry chips was too high, and that upcoming AMD processors won't have TDPs that exceed 95W.
AMD may eventually settle on a processor lineup with a 95W ceiling, but they're not there yet, and the easy-overclocking Black Editions are currently the most attractive Phenoms on the market for enthusiasts. We can, however, report that our board didn't seem to have any problems running a 9850 through our standard chipset test suiteat least on an open test bench. Your mileage may vary.
Like many recent motherboards, XFX's take on the 750a covers the voltage regulation circuitry with a beefy heatsink linked to the chipset cooler. Some have questioned whether connecting chipset and VRM cooling is a wise idea, since there's the potential for heat from the latter to creep down to the former. But the board's chipset is also sitting in a major hot spotbetween two graphics slots with little room for airflowso it's probably a good idea to have heat piped up to cooling fins that should sit right in front of a chassis exhaust port.XFX's chipset cooler is a low-profile affair, and it probably needs the heat pipe. The short fins do keep the heatsink out of the way of longer graphics cards, though. Unfortunately, longer double-wide cards installed in the green PCIe x16 slot (which also happens to be the primary graphics slot), will block access to three of the board's SATA ports. Had XFX moved the ports just a little further down the board, this wouldn't be an issue.
Next to the Serial ATA ports is a two-digit POST code display that's extremely useful when troubleshooting. XFX throws in onboard power, reset, and CMOS clear buttons, too. We're pleased to see CMOS reset buttons becoming more common, although we'd ideally like them in a more accessible location in the port cluster.Jumper blocks make an appearance in the slot stack, where XFX kicks it old-school with a manual SLI switch that controls PCIe lane routing. Switching from single-card to SLI mode involves popping four large jumper blocks, which really isn't a big deal since it's something you'll probably only have to do once. It would have been nice if XFX included a jumper pulling tool to make it easier to perform this bit of surgery while the board is still installed in a case, though.
In total, the board packs three PCI slots, a pair of PCI Express x1 slots, and two PCIe x16 slots for graphics. The top x16 slot isn't functional when running the board in single-card mode. However, the 750a's Hybrid SLI support allows compatible graphics cards to be used in conjunction with the mGPU to power additional displays.
Just to the left of the top PCIe x16 slot in the picture above, you can just make out a Marvell networking chip. For whatever reason, XFX chose to tap an auxiliary Gigabit Ethernet chip with the MD-A72P-7509 rather than using the GigE MAC integrated in nForce 750a chipset.Just about everything one might expect makes an appearance in the port cluster, including a choice of DVI and HDMI video outputs. You get external Serial ATA connectivity, too, but not Firewire. The lack of Firewire probably won't be a deal-breaker for many, but it is a disappointing omission on a $150 motherboard.
On the audio front, the board serves up two flavors of digital S/PDIF output backed by Realtek's ALC888 codec chip. This chip doesn't support on-the-fly Dolby Digital Live or DTS encoding, limiting multichannel digital output to sources with pre-encoded audio tracks, such as movies. If you want multichannel output in games, you'll need to switch to the board's analog audio outputs.While not technically a part of the port cluster, an internal Serial ATA port is tucked just behind the VGA port. This isn't an extra port so much as a conduit through which the port cluster's eSATA port is fed. To get the eSATA port to work, you have to string a Serial ATA cable up from one of the board's SATA ports to the one behind the port cluster.