ASUS M4A89GTD PRO/USB3
The 890GX-based mainboard from ASUS looks unusual as its developers have made a few original design decisions. It does not mean we have any complaints about the positioning of the components on the PCB. The ASUS M4A89GTD PRO/USB3 is a handy device and can hardly present any installation related problems.
The special feature of this mainboard is the way the two PCIe x16 slots for graphics cards are installed on it. The primary slot is farther from the CPU and can work in x16 mode. The second, gray-colored, slot works in x8 mode and can only be utilized for CrossFireX configurations. It means that if you have only one graphics card in your computer, you will have to install it closer to the mainboard's bottom edge, often blocking one of the two PCI slots.
Yet another peculiarity of the ASUS M4A89GTD PRO/USB3 is that it cannot automatically change the operation mode of the PCIe x16 slots. If there is only one graphics card in the system, a dummy card must be inserted into the gray PCIe x16 slot to switch the blue one from x8 into x16 mode. Perhaps not very handy for the end-user, this mechanism helped the manufacturer get rid of an electronic switch and make the mainboard a little bit cheaper.
This cost saving was useful as the manufacturer got the opportunity to install a number of onboard controllers on the M4A89GTD PRO/USB3 without increasing the price of the product much. First of all, there is a NEC controller supporting two USB 3.0 ports (the AMD SB850 South Bridge does not support this interface natively). ASUS's mainboard has a total of 14 USB ports. Two USB 3.0 and four USB 2.0 ports can be found on its back panel, and eight more are designed as onboard headers.
Additional controllers are also responsible for the mainboard's IEEE1394 interface, Gigabit Ethernet (ASUS preferred a PCIe x1 Realtek 8111E controller to the MAC controller integrated into the chipset), and eSATA. Thus, besides the six mentioned USB ports, the mainboard's back panel offers one IEEE1394 port, a network port (RJ-45), one eSATA connector, and a PS/2 port for keyboard. There are also six analog audio sockets and one optical SPDIF connector implemented through an eight-channel controller ALC892. The mainboard also offers as many as three interfaces to connect a monitor to the integrated graphics core: D-Sub, DVI and HDMI.
The CPU power circuit consists of an eight-channel voltage regulator (officially supporting CPUs with a TDP of 140 watts), with two more phases dedicated to the CPU-integrated North Bridge (which comprises a memory controller and L3 cache). It is cooled by a massive aluminum heatsink connected to the heatsink on the chipset's North Bridge.
The heatsink on the AMD 890GX chip is secured firmly with screws whereas the heatsink on the voltage regulator is fastened with two spring-loaded plastic locks and the thermal interface doesn't look trustworthy, resembling a piece of insulation tape. ASUS's engineers must have relied on the sheer size of the heatsink, but the large size made it necessary to install a rather funny and tall 8-pin ATX power connector.
The mainboard is free from enthusiast-targeted features like diagnostic LEDs or Power On, Reset and Clear CMOS buttons. Instead, there is a MemOK button and two switches: Turbo Key II and Core Unlocker. The button can be pressed to start the mainboard up with failsafe memory settings, preventing the system from hanging up. The Turbo Key II feature is for automatic CPU overclocking. And Core Unlocker is ASUS's very exclusive switch that unlocks disabled cores in dual- and triple-core processors. That's in fact the replacement to ACC technology.