Now common on many Lian Li products as well as on other brands, the layout/design of the PC-Q07 was groundbreaking at the time. By putting the power supply unit (PSU) in parallel with the motherboard, Lian Li created a delicate small case that, unlike other slim cases, can hold standard components: ATX PSU, 5.25” Optical Disk Drive (ODD), 3.5” HDD. There is sacrifice of course, the major one being less clearance for CPU heat sink. But considering Mini-ITX systems are usually not power-hungry, the trade-off makes sense and is likely worth it. Plus, the unique design makes PC-Q07 very playable. It has been widely welcomed, as can be seen from the number of threads related to this case on hardware forums. People share their experience with the case, provide compatibility checks, show their modification projects. It has become a healthy community of PC-Q07 users, and here I am to present my part.

Lots of the forum threads are related to cooling, an inevitable issue for slim cases. This is also what I am going to investigate today. My motivation comes from the excessive noise and high operating temperature of the system in my initial setup, so I am looking for a workaround. My two objectives are:

1. Find out if Scythe Big Shuriken SCBSK-1000 120mm CPU Cooler will improve cooling and if so, by how much.

2. Find out if the orientation of PSU makes a difference in cooling.

First of all, why do I think PSU orientation might make a difference?

In a standard mid-tower ATX case, air absorbed by the PSU probably does not matter. Air flow is taken care of by dedicated case fans. However, in the PC-Q07 where no case fans exist at all, the only thing that actively puts air out of the case is the PSU. This is why where the PSU takes air might make a difference. The large area of vent holes on the side panel indicates that Lian Li wants me to put the PSU so that its fan faces the side panel and thereby takes air from the (out)side, forming an independent cooling cycle that has nothing to do with other components. But what if the PSU fan faces inward and takes air from above the CPU heat sink? In this way the hot air dissipated by the CPU heat sink is conveniently absorbed by the PSU fan and then sent out of the case, which might make the system cooler.

There is one concern though. If the PSU fan faces inward, it and the CPU fan absorbs air from the same space, but blow in different direction. Will they end up fighting for air and make cooling less efficient? Let’s find out.

Independent variables are:

  1. the type of CPU heat sink used (Intel stock cooler vs. Scythe Big Shuriken SCBSK-1000 120mm CPU Cooler)
  2. the orientation of PSU (facing inward vs. facing outward/side).

Two independent variables, so four different configurations.

Test method: Use FurMark and wPrime 1024M to full load GPU and CPU, respectively. Monitor temperature of both.

Dependent variables: CPU temperature and GPU temperature towards the end of a wPrime 1024M run.

1. PSU facing outward, Intel stock cooler

2. PSU facing outward, Scythe Big Shuriken

3. PSU facing inward, Intel stock cooler

4. PSU facing inward, Scythe Big Shuriken

I rearrange the results in the table below:

PSU fan faces Heatsink Max CPU Temp Max GPU Temp
side stock 88 85
board Big Shuriken 66 77
side Big Shuriken 74 85
board stock 78 73

This is not a perfect test setup. I didn’t even run multiple times and take average. But I believe if the effect of one variable is significant, small variations won’t be able to cover up the overall trend, though they may reverse the results in some borderline cases.

So, clearly, as far as CPU temperature is concerned, PSU facing inward is better than it facing outward (9 degree difference on average).  Scythe Big Shuriken is far superior to the Intel stock cooler. Here we are talking about a 13 degree difference on average. Also, the combination of the two gives the best outcome in the entire test, which means that “fighting for air” either isn’t an issue or its effect isn’t big enough to offset the huge benefit brought by a better heatsink and better orientation of PSU.

Things get interesting on the GPU side. It is still true that PSU facing inward performs better than PSU facing outward (10 degree difference on average),  but the use of Scythe Big Shuriken doesn’t make GPU any cooler, if not hotter. I wonder why. The difference is small, though. 0 or 4 degree could be totally explained by some error.

Update:

An even better setup is to reverse the CPU fan so that it blows toward the PSU fan, where the two fans together creating a wind tunnel. See my test on the effect of reversing the CPU fan here.

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