GMC AVC-S7: Ultra-Slim HTPC Case

Today we are going to talk about the slimmest home theater PC case that will look great among other audio- and video- devices in your living room.

by Aleksey Meyev
10/04/2009 | 01:56 PM

A modern computer is an excellent platform for a home multimedia center. It offers a large and easily accessed storage for movies, music and photographs, flexibly configured interface and codecs, simple connectivity for audio systems and displays. However, home theater PCs have not become ubiquitous because there are few ready-made models whereas building a compact, quiet, handy, easy-to-use and remotely controlled system with your own hands may be too much of a task for most users. As a result, people prefer to stick to special-purpose electronic appliances while others use a standard PC without a remote control. And others yet use media players that offer wide functionality now while being about as expensive as a computer. Still, it is the user who takes on the daunting task of building an HTPC with his own hands that has the most freedom in configuring his home theater arrangement.


In this review I will be talking about one of the most important components that make up an HTPC. A compact system case. The AVC-S7 model from GMC is specially designed for a home multimedia system. You may remember our reviews of the extraordinary GMC R4 Bulldozer and the GMC AVC-K2 which is an HTPC case designed as a typical tower and allowing to assemble a full-featured PC configuration. The AVC-S7 is a more traditional variant of an HTPC case. It is a slim and flat box that can easily fit into a stand for other home hi-fi equipment. The AVC-S7 is even slimmer than usual, measuring no more than 7 centimeters in height.

Closer Look at GMC AVC-S7

Exterior Design and Software

HTPC cases are usually designed as other hi-fi devices like a neat flat box. The designer’s logic is easy to grasp. There are well-established stereotypes that must be followed. It wouldn’t be aesthetic to put an HTPC with a gaudy front panel shimming with multicolored LEDs onto a special stand next to expensive hi-fi products.

So, GMC doesn’t go against the general trends. The AVC-S7 is disguised as a high-class DVD player. You can hardly suspect that this slim thing with a characteristic disc slot in the middle of the front panel and a row of familiar icons in the bottom corner is actually a computer. The small height of the case is highly impressive. A regular HTPC case is about two times as tall as that.

Besides the optical drive slot, there are two buttons on the front panel. One of them opens the drive’s tray (it is designed in an original way and sinks but very little under your finger) and the other turns the thing on. But let’s push the front panel as the word painted on it prompts us.

The bottom part of the front panel, made from translucent dark plastic, flips down and opens access to a gorgeous selection of connectors and buttons. There is a two-line display in the center that shows text information. I will discuss its functionality shortly. To the left of it, there is a multi-format card-reader integrated into the front panel. That’s quite all right: I don’t think anyone will want an external 3.5-inch bay in his HTPC whereas the neatly integrated card-reader is going to come in handy considering the current popularity of various memory cards. On the right of the front panel there are buttons and connectors: two USB ports (placed too close to each other, so you won’t be able to plug two thick flash drives in simultaneously), two audio connectors (microphone and headphones), and a FireWire port. The buttons are a 4-way joystick, AV center, Back, and Reset. The latter is the same shape as others and can be pressed accidentally. I guess this button might be moved to the back in an HTPC case or discarded altogether. The buttons and connectors are all accompanied with labels or icons which are also duplicated on the back of the flip-down cover.

Before describing the case further, I want to tell you about the buttons and the display. The AVC-S7 employs a management system that is similar to the one in the GMC AVC-K2. It is developed by SoundGraph and combines a controller connected via USB to the mainboard, a display, a remote controller and software. The software consists of two applications: iMon Manager is responsible for the display and the interaction with the buttons on the case and the remote control. The iMedian HD application is a multimedia shell similar to Microsoft’s MediaCenter (you may also be familiar with MediaPortal, which is yet another popular multimedia shell). It serves as a graphical interface, providing access to files and features from the remote control.

SoundGraph’s solutions are also sold as separate products: a kit consisting of a display and remote control (the software is included, too). As you understand, GMC just installed an OEM version of the solution into this HTPC case.

As part of that system, the 2-line display I have mentioned above outputs diverse information from time/date to sound equalizer, song info, weather forecast and news reports from the channels the user has specified in the iMon Manager settings.

After you turn the computer on and install drivers and software, the display will go on showing its information even when the computer is shut down. This is implemented by the connection of the management system to the standard 24-pin mainboard connector so it can be powered by the 5V standby source. It is this power adapter that you can see in the photo above together with the system’s USB connector. By the way, the USB connector is equipped with an adapter for the mainboard’s onboard header. Unlike many Chinese manufacturers, GMC is aware that there are no standard USB connectors inside a computer.

Now let’s get back to the functionality of the management system. The buttons on the front panel of the case are designed for interaction with the computer without a mouse and keyboard: the 4-way joystick is a good substitute for a mouse while the Back button works as Escape. The AV Center button evokes the iMedian HD shell by default.

The remote control included into the kit has about the same functionality as other such devices. It offers full control over the media center and can be used to perform some simple actions in the OS: the mouse pointer can be moved about by means of the joystick in the center of the control (and I should say it is a lot of fun). The remote control is fully compatible with standard MediaCenter controls from Microsoft, so you can easily use it with most applications including Windows MediaCenter proper. It is free from any ergonomic innovations, but has a handy size and responsive buttons.

And finally I want to say a few words about the software part of the system: the iMon Manager and iMedian applications.


Being a tool for controlling the buttons and display on the front panel of the case, iMon Manager is inconspicuous but offers wide setup opportunities. You can set up almost anything you can think of, the selection of commands being especially impressive. You can assign almost any function to any button of the remote control or system case. If you are not satisfied with the standard, system or iMedian functions, you can write your own macros. You can also set up the information output for the display: weather forecast, news, email notifications, system info, playback info, mode selection. Yes, the setting up may take a long time, but in the end the system will be just the way you want it. And do you often see home electronic devices that can check out your email box?


One of the few visible signs of iMon’s presence in the system is the list of quick-launch applications. This list is rather short originally, but you can extend it as much as you like. You can also set up the operation of the exclusive applications already on the list. It is good that the default list includes such handy applications as an onscreen keyboard, a quick change of display resolution (may be handy if you connect a TV-set to the computer), and an alarm clock. So, that’s a menu for launching your frequently used applications.


The iMedian shell is, on the contrary, very conspicuous. It is within this shell that you interact with the media center’s features. Like with other such programs, you first have to choose and scan folders with photographs, music and videos, specify codecs to use, set up your TV-tuner if you’ve got one, enter the addresses from which you are going to get news, weather reports and webcasts. It is deep within such programs that you usually find problems like incompatibility with codecs or with rare TV-tuner models, or unhandy menus, etc. I did not have any problems with iMedian, though. All of its features seemed to work normally.

So, this management system is not as simple as to be set up to your taste in half an hour, but its functionality is as wide as with alternative solutions.

Now let’s get back to the system case.

The case is low and can hardly accommodate any cooling fans. Therefore it is cooled passively. There is a large array of round holes in the top panel of the case and vent slits in the side panels. This system case is going to accumulate dust, so you will have to use your vacuum-cleaner on it often.

The back panel is an unusual view. Even low-profile expansion cards cannot fit into such a slim case, so there are no expansion-slot brackets here. There is no basic I/O shield for the mainboard, either. On the other hand, there are so many configurations of mainboard connectors available that you have to install the I/O shield included with the mainboard anyway (it is even odd that system case makers include a “standard” I/O shield that does not fit any real mainboard anymore).

The single slit in the center of the back panel is interesting. Judging by the characteristic protrusion next to it, the case has a riser card that allows to install an expansion card in parallel to the mainboard.

The system case does not support standard ATX power supplies due to its small height. It only supports SFX models. My sample of the AVC-S7 was equipped with a Sirtec High Power SFX-270A1 that has an output power of 270 watts and is cooled with two 60mm fans. This PSU complies with the SFX 3.0 standard which is not new, but still viable (the newer versions of the standard have lower requirements to the load capacity of the +5V and +3.3V rails).

The PSU is equipped with the following cables and connectors:

I did not test the PSU because its capabilities are obviously enough for any reasonable HTPC configuration you can assemble in such a compact case. Its manufacturer – Sirtec – has a good reputation.

The system case stands on four massive plastic feet that have metallic rims and rubber pads in order to absorb vibrations.

Internal Structure and System Assembly

Now let’s take off the U-shaped cover and take a look inside.

The interior is ascetic but there are a lot of cables in it. The chassis is rigid and high quality. Everything is solid and serious, there are no sharp, unfinished edges. The mainboard’s installation posts are already inserted into the bottom of the case.

The most interesting things can be found near the front panel. It is the hardware part of the management system I described above: a card with a bunch of cables.

A slim optical drive is accommodated in the center of the front panel. Such models are employed in notebooks. It is a DVD/CD-RW drive from Panasonic (the CW-8124-B model). What I don’t like in this drive is that it cannot even burn DVDs, let alone read BDs. Moreover, it has a PATA interface. This interface is steadily being abandoned by mainboard makers, but GMC sticks to it for some reason. Laying out a broad PATA cable in such a compact system case is no fun, really.

The single HDD bay is to the right of the optical drive in the photo.

The HDD is fastened with screws to a detachable metallic thing that can hardly be called rails or a cage. The bottom part of the thing is empty and might let in another HDD, but this space is partially taken by the internal part of the card-reader. I guess the component layout might have been changed to accommodate two HDDs. Having only one HDD is not a problem today as modern HDDs offer large storage and there are also external storage media like NASes, but two internal HDDs would be even better.

All of this is fastened to the chassis with ordinary screws.

There is indeed a riser card near the PSU, above the mainboard’s expansion slots. That’s where I was disappointed again: the card supports PCI devices only. It is meant for a TV-tuner obviously, but even tuners have begun to transition to PCIe x1 interface. A user may also want to install a single-slot graphics card or a discrete sound card instead of a TV-tuner. So, although this riser card is better than no expansion cards at all, but I would like to see a PCI-E riser card instead (it is hard to buy one in retail and harder yet to install).

Winding up the descriptive section of the review, I want to show you the most appropriate accessory to this system case, a low-profile cooler. To remind you, the system case has a very small height. There is a mere 55 millimeters from the mainboard to the top panel, so even not all of low-profile coolers will fit in. Therefore GMC supplies a cooler together with the system case. The cooler represents a standard design similar to the popular Zalman CNPS7700. It is all copper and should be efficient enough. But again GMC is lagging behind somewhat. The cooler’s fan has a 3-pin connector and is going to work at full speed only on most modern mainboards whose fan management systems are meant for 4-pin fan connection.

It is easy to install the cooler: it can be secured on Socket 939 by means of clips on the cooler itself. For Socket 775, there is a simple installation frame which is fastened to the mainboard with four pegs.

I had little problems assembling a computer in this small system case. I did not even have to remove the central strut: I just put the mainboard’s end under it. Laying out the cables was not easy as there is little room inside the case. And there should be some free space in the assembled case for some air flow. So, I tucked most of the cables under the optical drive whereas the unused cables of the PSU were placed neatly near the HDD.

It is these power cables that presented the biggest problem to me. While most of the power connectors are not needed (the case cannot accommodate so many devices), the 4-pin 12V connector did not reach to the mainboard’s header by about 3 centimeters. That’s a problem indeed because this header is located in that very corner, behind the CPU, on most mainboards. I had to use an old adapter from a Molex connector to power the mainboard, but I doubt many users have it.

I decided to assemble and test this system in two variants because I had a boxed cooler included with Intel’s junior processors – it is a small aluminum “pancake” that fits nicely into this system case. I used this opportunity to check out the efficiency of the cooler included with the system case.

When the system case is turned on, the LED of the Power button looks too bright to me. If you leave the computer working for a night, it can serve as a night lamp. Compared with it, text on the display looks somewhat dull. To read it from a distance, you will have to strain your eyes, especially if the ambient lighting is more or less good.

It is not the problem of the display, which is appropriately bright, but rather of the too dark plastic of the flip-down cover in front of it. This problem can’t be solved without changing the design of that cover.

Testbed and Methods

The tests are performed with a closed and assembled system case at a constant ambient temperature of 23° that is maintained by an air conditioner. Most users are likely to prefer quieter PCs, so we set the CPU cooler and the system fans (connected to the mainboard) into the Silence mode. If the system case has its own controller, the fans connected to it are set at minimum speed, too. We did not modify the configuration of airflows.

The following configuration was assembled in the tested system case:

The microATX mainboard I used does not support a system bus frequency of 1333MHz, so the E6850 processor was clocked at 266x9=2400MHz rather than at its standard 3GHz. Anyway, the heat dissipation of this CPU, even at a reduced frequency, is comparable to today’s 45nm dual-core CPUs and higher than that of Atom CPUs. I don’t think that users are going to install a more advanced processor into an HTPC anyway. Today’s entry-level CPUs are more than enough for decoding HD video with support from the integrated graphics core.

The CPU temperature was read with the ASUS PC Probe program supplied with the mainboard. The HDD temperature was reported by HDD Thermometer. The fan speeds were measured with an optical tachometer Velleman DTO2234.

There were the following test modes:

Each temperature was read after half an hour of operation in each test mode, i.e. when the temperatures of the components had stabilized.

As a reference point, here are the temperatures of a similar configuration working without a system case (“open testbed”).

The system case configuration differed from the open testbed in having no graphics card and being equipped with different coolers (the open testbed was tested with a Zalman CNPS9500 AT).

The level of noise was evaluated subjectively.

Test Results

The following table shows the temperatures of components.

There is nothing extraordinary here. The system case copes with cooling under any load.

Noise is quite a different thing, though. The fan of the included cooler is rotating at 2800rpm, providing good cooling but producing too much noise as the mainboard with a 4-pin fan connector cannot reduce its speed. Compared to it, the boxed cooler from Intel is much quieter at 1800rpm. Moreover, its speed lowered to 1000rpm under low CPU loads, making it virtually silent.

These are but trifles, however, compared with the noise produced by the power supply. Its two 60mm fans were doing their best to cope it and were producing a loud and irritating buzz. They were louder than the heads of the HDD during active seek! Such noise is unacceptable for an HTPC. Perhaps it won’t be disturbing when you are watching an action movie, but you can hardly relax to some soft music as the high-frequency buzz will distract you.

Now let’s compare the case with the open testbed.

When the system is idle, the components are cooled but slightly better on the open testbed. Take note of the difference in the CPU temperature between the two coolers. The included cooler is almost as good as the bulky Zalman CNPS9500 AT whereas Intel’s boxed cooler is considerably worse.

The hard disk drive feels good enough even under load. It is cooled by the air that flows into the power supply. The air flow is strong due to the quickly rotating fans.

The included cooler copes with high CPU load whereas Intel’s aluminum cooler fails. The included cooler is made from copper and has a ribbed heatsink. The noisy fan is its only downside, but the PSU is even louder.

Running 3DMark on this system may seem ludicrous, but this benchmark can be viewed as a typical average CPU load. Intel’s cooler accelerates to its maximum speed and catches up with the opponent, proving its worth.


The GMC AVC-S7 is a rather expensive but interesting product that represents an original platform for building an HTPC. Its exterior is all right and its chassis is good overall. It is slim and disguises as an ordinary DVD player. It has an integrated display with appropriate software support, can be operated with a remote control or buttons, and comes with a slot-loaded optical drive. These are all hefty arguments in favor of it.

Alas, the use of outdated components and a very noisy power supply are a serious downside. The power supply just calls for replacement as such a high level of noise is unacceptable for an HTPC. The AVC-S7 might be viewed as a platform for enthusiasts to experiment with but it is too expensive for that. Paying so much money, you want to get a modern product that does not need any manual improvements.