I've made my mark

Introduction

A while ago, I’ve designed a home theatre PC build for regular TV viewing and recording. Recently I’ve followed it up with an unceremonious unboxing of various parts involved in that HTPC. So the thing that comes after unboxing is putting it together. So in this article, I’ll share my thoughts and experiences while building this machine.

Several factors are of importance to this build: power efficiency, noise and heat while at the same time it must be capable of high definition recording and playback. These factors are typical for many other home theatre builds.

Components

Motherboard

In my design, I chose the J&W MINIX 780G mini-ITX motherboard, for its on-board Radeon HD3200 graphics chip. It came in a slightly unconventional packaging design, but it does include all of the usual accessories.

If you look carefully at the accessories, they have also included a small 40mm fan that is meant to be mounted onto the northbridge heatsink. Since I would like the home theatre PC as quiet as possible, I have opted not to mount that fan onto the heatsink. It’s also noteworthy that earlier packages of this motherboard did not come with a fan. So there might be heat issues in extreme situations.

Memory

One benefit of this board over most other mini-ITX boards is that it actually supports two banks of memory, running in dual-channel mode. I went with a pair of cheap Kingston KVR800D2S5/2G DDR2-800 memory modules.

Storage

The hard drive is actually not very important amongst the scheme of things. As long as its capacity is big enough to hold the system and media files, it’ll be fine. It won’t contribute much to the performance either, since an HTPC will not be thrashing the disk while playing or recording videos. I’ve kept it to the Samsung HD103UJ 1TB SATA2 7200 RPM drive with 32MB cache.

Optical media

Now here’s an interesting one. In the previous design, I’ve spec’d out a Blu-Ray combo drive. But, several things came up since:

1. I don’t actually watch Blu Ray movies very often
2. I don’t even use DVDs.
3. The drive was out of stock.

In the end, the 5.25” slot in the case was just left unoccupied. And it was just fine. That’s right, no optical drive.

TV Card

Not too much to say here apart from the fact that it works. The Leadtek PxDTV2300H PCIe x1 Hybrid DVB-T/Analog TV tuner card works great in Windows Media Centre, and it’s all good. The included software for the infra-red remote control also works well in Windows 7. It functions as a WinFast specific remote, but it’s easily switchable to function as a generic Windows Media Centre remote.

The bundled infra-red header plugs into the back pane of the TV card. I then attached this to the front of the case, into the black region to make the ugliness less obvious.

Case

I went along with the Aywun MI-100 mini-ITX case as per the design. It’s cheap, small and has a full size 5.25” drive bay. So, If I actually were to install a DVD drive, I can re-use one from a regular desktop, which costs much less than a slim-type one.

Another advantage of this case is, it comes with a 220W power supply which is more than enough for a low power HTPC running an onboard graphics chip.

The layout of the case is acceptable in its ease of assembly, but unfortunately airflow is severely limited. I know that all small form factor cases have a similar problem, but this case doesn’t event have a mount for case ventilation fan. It relies on the power supply fan to draw hot air outside of the case, which is inadequate if we would like to the fan to run at low speed (i.e. low noise). Cable management features are nonexistent, which I thought was a bit of a disappointment especially in the small form factor. Many PC builders don’t realise that good cable management plays a nontrivial role in cooling. If cool air can’t flow from outside through to the hot components inside because the cables are in the way, then the computer will start cooking from the inside.

Assembly

To prevent this article from dragging on, I’m not actually going to document the assembly procedure. That would be a little boring. Instead, I’ll highlight some interesting things that came about during assembly.

Even though I’ve build PCs countless times, this is the first time I’ve worked with the mini-ITX form factor. And because of this, one challenge that came about is obviously the space that is available.

The Aywun MI-100 is laid out in such a way that gives the impression that designers aim to cram as much as possible. If we take a closer look, we can see that the SFX power supply (which is about half the size of a standard ATX PSU) sits over the motherboard. What is immediately obvious is that a low profile heat sink and fan combination is required, since the stock heat sink that comes with the CPU box will not fit under in the 5cm clearance available.

On further examination, I realised that something is not right. The PSU fan sits over the CPU, drawing hot air out of the case. If I were to mount a CPU heat sink and fan underneath, then I would create unnecessary turbulence (= noise + cooling inefficiency) since the CPU fan draws cooler air above and forces it down onto the hot CPU heat sink. So, what can I do to alleviate this problem?

One way is to reverse the CPU heat sink so that it draws hot air away from the heat sink, blowing upwards. In the end I chose to use the stock heat sink after removing the CPU fan so that it fits underneath the PSU. And it’s a tight fit. In fact, I was surprised that the stock, full-size heat sink actually fits. Now the question that remains is, is the heat performance of this “passive” cooling adequate for this system?

The reason why passive is in quotation is because it’s not totally passive. But having the top of the heat sink so close to the PSU fan, the fan is now functioning as the PSU fan, case fan and the CPU fan.

On the topic of air flow, it may seem that there are plenty of holes around the case, which should give it plenty of air flow, right? Well here’s one smart thing the case designers have come up with: The hard drive mounts vertically along the side. Looking at where things are, it seems pretty good, especially since the hard drive is now out of the way, looks clean and there’s nothing terribly wrong with having the hard drive vertical. Except when we look at the implications of this design choice in context of this particular case.

The hard drive now perfectly block out much of the holes along the side of the case. Say goodbye to any kind of airflow you hoped for.

Now, if we combine this with the PCIe card on the other side of the case, we now have the grills on both sides of the case blocked out. Ingenious, isn’t it? Having a half-height TV card here helps a little I guess by allowing at least a bit of air through, but there are quite serious air flow issues here as we’ve seen already.

One annoyance I’ve found with this PC so far is that the 220W PSU that came with the case runs quite loud. The fan itself produces a great deal of noise, and it does not lower the fan speed depending on the temperature. I have replaced this with an older SFX PSU that is quiet, but it uses a 20-pin ATX Molex plug rather than the 24-pin ATX 2.0 connector on the motherboard. The solution is rather simple because ATX 2.0 is an extension of ATX; the 4 extra pins provide extra power rails to handle additional power load. This computer doesn’t draw that much power, so I would say it’s acceptable to go without them.

Let’s take a look at how well this solution holds up to stress.

Temperatures

One of the first things I’m interested in above all else is its thermal performance. First of all, the mini-ITX form factor is matched with a relatively tiny chassis. It’s also quite obvious that the MI-100 case had not been designed with airflow in mind given that there are no case fans, and the only grills at the sides are blocked by either the hard drive or the PCIe card.

To place the system under load, I used OCCT 3.0.1, which stands for OverClock Checking Tool. Essentially, it runs a series of calculations repeatedly and checks if the calculation is correct. Even though it’s designed for overclocking, it is also quite good as just a load runner to put the CPU usage up to 100%.

So how were the measurements made? I took the CPU core voltage reading and looked at the average temperature of the two CPU cores from OCCT. Power draw was measured at the plug using a cheap (imprecise) digital wattmeter, so this includes the PSU losses as well. The room temperature at time of measurement was 17 degrees Celsius.

75 degrees Celsius is a little on the high side, but it’s still within normal operating temperatures of the CPU. Anyway, it would still be better if the temperatures were just a little lower.

Power Consumption

Just like my laptop, a natural thermal management solution is to undervolt the CPU. This means, have the CPU run on a lower core voltage than stock values. So I went into the BIOS settings, and set Vcore to a fixed 1.150V. This turns out to the the lowest setting I can go before OCCT starts to report that the processor would have calculation errors.

With the system temperature now maxing out at 65 degrees, I’m quite happy to leave it at this level. Setting the voltage to a fixed value also meant that at low system load, it won’t scale down to 0.94V, drawing a bit more power when the system is idle. However I’m happy to let this happen because it means my system can run cooler under load.

If power consumption is an even greater concern because of the long hours the computer will be switched on for, an option is to both underclock and undervolt it at the same time. However, this would be beyond the scope of this article.

Performance

The software setup is pretty basic. It’s a clean Windows 7 x64 RC installation, and only using Microsoft’s graphics drivers. The display is connected via D-Sub (I don’t actually have an HDMI monitor), and it’s running at a resolution of 1280×1024 @60Hz.

The Windows Experience Index (WEI) is a great way to get things started. It’s simple to use and it comes with Windows. Let’s see how it scored:

Which gives it a WEI base score of 3.9. It’s not too bad for an integrated graphics. I think it’s worth noting here that it’s possible to increase the memory performance up to 7.1, by setting the onboard graphics to use only the sideport memory, and not have any share of the system memory (megabytes and cycles). But, the downside is that the graphics performance would have such a negative impact that even running Media Centre at full screen lags. I couldn’t work out why that is, but it’s fixed when system memory is shared with the graphics chip.

Next, to see how well the box views digital television, I measured CPU utilisation using Task Manager, while using WinFast PVR2 to view a digital TV channel. I tested both a standard definition channel and a high definition channel, and let’s see if the “hardware acceleration” setting in PVR2 has any effect. By default, this setting is disabled. I can only presume it’s because the Digital TV Tuner card itself doesn’t include hardware decoding capabilities.

So why is there such a performance boost? The video is playing smoothly, and at such a high resolution, but not much CPU usage when hardware acceleration is turned on. But if the tuner card doesn’t have a hardware decoder and the CPU isn’t doing the work, what is actually doing the processing for me?

I can only attribute this to the graphics card. If I’m correct, then it must be that the onboard Radeon HD 3200 has taken over the job of decoding the video signal.

Now even though it’s not a gaming machine, let’s benchmark the system for gaming performance. I used the standard toolkit for measuring 3D rendering performance, made by FutureMark.

3DMark06: 1359 (SM2.0 = 447, SM3.0 = 519, CPU = 1860)
3DMark Vantage: E1918 (GPU = 1644, CPU = 3839)

In other words, the onboard Radeon HD 3200 will not play your latest games. But for an HTPC, that’s ok.

Final Thoughts

The J&W MINIX 780G is an excellent motherboard that offers great control over the hardware components, and its onboard Radeon HD3200 handles media playback without any problems. With two DDR2 slots, it’s not difficult to fit out a PC with 4GB of memory. Not that an HTPC will need 4GB, but it’s better than  many other motherboards in its class.

For a mini-ITX system, the system case is very important. It’s worth spending a bit more of the budget on a better designed case. I would not recommend running an AMD socket AM2 or Intel socket 775 system using the Aywun MI-100 purely because of its poor air flow and layout design.

The AMD Athlon 64 x2 5050e “energy efficient” CPU has a power dissipation rating of 45W, which is much lower than the regular Athlon 64 x2 counterparts. This is quite an important consideration when looking at the small mini-ITX form factor due to limited cooling capabilities. With this CPU, I have shown that it is possible to achieve stable operation using a passively cooled stock heat sink although some may not be happy with the high system temperatures under full load.

In normal operation, even during high definition video playback, the system load is kept quite low thanks to hardware acceleration by the onboard Radeon HD3200 graphics chip. So, it is safe to say that the normal system temperature is at an acceptable level, especially with AMD’s Cool ‘n’ Quiet technology. If there are concerns regarding the system temperature, one possible countermeasure is to limit the maximum CPU frequency, and this setting can be found within the motherboard BIOS settings.

This system is quite capable in terms of performance. Using a regular dual core Athlon 64 x2, the raw CPU grunt outperforms that of an Intel Atom found on many other mini-ITX systems. Together with onboard Radeon HD3200 graphics, this PC is a fast yet power efficient HTPC that can potentially double up as your main PC without feeling dragged behind.

Tags: AM2, AMD, Athlon, Aywun, benchmark, Hardware, heat, HTPC, performance, power, Radeon