Bringing it to the desktop: Asus' N4L-VM DH
Despite its new pin layout, the Core Duo's transition to the desktop has been eased considerably by the success of Pentium M desktop boards and by the inclusion of the Core Duo in a non-mobile role as part of Intel's Viiv platform for home theater PCs. The Viiv platform requires a dual-core Intel processor, and obviously, Core Duo is a more attractive prospect for system builders looking to produce a quiet PC for the living room than the hotter, power-hungry Pentium D. A number of motherboard makers have announced mobos for the Core Duo, many of them designed to fit into the mini-ATX form factor and bristling with the ports needed for driving home-theater-class audio and video equipment.
The Asus N4L-DM VH was the first of these boards to make its way into our labs, and so it captured our undivided attention. This is a micro-ATX-sized board with little of the flair of Asus's high-end mobos, but what's important is its ability to support a Core Duo CPU. Asus went all out on the mobile theme with this one, basing the board on a true mobile chipset, the 945GM north bridge and ICH7-M south bridgeit's like a laptop board with desktop-style DIMM and PCI slots. Some other manufacturers have opted to use desktop chipsets like the 975X in their Core Duo desktop boards, but the mobile chipset ought to draw less power and generate less heat than a desktop version would. As you can see, the north bridge requires only passive cooling, and the ICH7-M needs no heat sink at all.
The mobile chipset is probably to blame for the lack of expansion options, though. The board has only two DIMM slots (although that would matter more if the Core Duo had 64-bit addressing) and only two SATA ports off of the ICH7-M. The other two SATA ports come from an auxiliary SATA controller chip from JMicron, and one of those two ports is an external eSATA job.
The port selection around back of the N4L-VM DH is a little bit bewildering for a "digital home" type product aimed at home theater PCs. Things start out well. The board has eight-channel analog audio ports, as well as optical and coaxial outputs for digital audiojust what you'd want. It also has that eSATA port for adding external storage, and the Ethernet port is of the Gigabit variety. All of these things make sense. However, the N4L-VM's only video output is a VGA portthere's no DVI port for driving an HDTV, no HDMI connector, no component output, and no TV out of any kind. Fortunately, Asus does sell a DVI-out card separately, but these choices are a bit puzzling for a potential HTPC board. Perhaps they simply expected folks to use the PCI-E x16 slot for graphics and only included the VGA port since the graphics capabilities were already built into the chipset. At any rate, my ideal HTPC motherboard would include a better selection of video output ports and an 802.11g wireless networking capability.
You're not likely to receive your Core Duo processor with a "stock" cooler, and so Asus includes a custom one with the motherboard, to be secured by a pair of metal hoops protruding from either side of the CPU socket. Installing and removing the thing is fairly easy, and the fan is virtually silent when running under normal loads with the board's temperature-based fan speed control enabled. It does become audible when the CPU is running something intensive like a multi-threaded rendering app, but even then, it's barely noticeable from a few feet away.
Just for the sake of comparison, here's a look at Asus's Core Duo cooler next to the type of cooler we use to keep a Pentium Extreme Edition processor running OK without too much noise: a Zalman CNPS9500 LED.
My only complaint about the N4L-VM's cooling setup is that it doesn't allow for the mounting of any type of standard desktop cooler, like a Socket 478-compliant one. The ability to use a beefier cooler might lead to some intriguing options, like a totally passive CPU cooling setup or particularly egregious overclocking.
Trouble in paradise?
Obviously, our N4L-VM DH review unit was one of the first of these boards available, and it still had some rough edges. After too many hours of troubleshooting, we were able to pinpoint a problem with the board's AHCI implementation on its two ICH7-M-connected SATA ports. AHCI is the SATA extension that allows for newer features like device hot-plugging and Native Command Queuing. NCQ can affect performance, so we naturally wanted to have it enabled, but turning on AHCI resulted in a more or less constant 40% CPU utilization in Windows, apparently caused by hardware interrupts. Our only option was to turn off AHCI and test performance without NCQ enabled. Asus confirmed to us that they were able to reproduce the problem, and they say they're looking into it with Intel.
Another problem we encountered was an annoying tendency for the system to fail to come back after a warm reboot about 50% of the time. We'd have to shut down the system power at the PSU, forcing a cold boot, in order to recover. Each time we went through this process, the board would come up during POST after the cold boot and say that overclocking had failed. We'd then have to press F1 enter the BIOS and exit in order to for the system to continue booting. This is what's known in the industry as "really frickin' annoying." We tried using a couple of different big name brands of 1GB DDR2 DIMMs in the boardCorsair and Crucialand had the same problem with both. Perhaps dialing back to way more conservative memory timings would have helped, but the 3-4-4-10 timings we used were within the tolerances of the DIMMs, and the system was otherwise stable in MemTest86+ and in every application in our test suite. Let's hope Asus can resolve this problem, and the AHCI issue, with a future BIOS update.
The last problem we ran into on our way to mobile-on-desktop nirvana was the N4L-VM DH's incredibly limited set of BIOS options for overclocking. There's no control over CPU voltage, no option to set the memory frequency, no option to change the CPU multiplier, no means of controlling clock ratios between different components. The board does offer your choice of DDR2 voltages from 1.8V to 2.1V, which is definitely better than nothing.
We tried overclocking the Core Duo, but when the system wouldn't boot our stock 2.16GHz processor at 2.3GHz, we were left with no real tweaking options to help resolve the problem.
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