Thursday, August 18, 2022

Semi-passive PC cooling. Selection of components and setting up cooling schemes


Not so long ago, we assembled a gaming PC with semi-passive cooling for 100,000 rubles . Then we did not go into details and only briefly touched on the reasons for choosing certain components. It’s time to take a closer look at the process of building and setting up a semi-passive configuration.

What is it for
As a rule, the role of a gaming station and a working computer is performed by the same system unit. During the game, the noise of the cooling system is drowned out by the sounds and special effects of the game. But during work, it can be distracting and annoying.

The goal of this article is to build an all-in-one computer for work and play that is completely silent in low load mode and as quiet as possible during serious computing. At the same time, the cooling system automatically switches from passive to active cooling mode and vice versa.

Perhaps most users will not hear the active cooling system, the fans of which rotate at low speeds. But, there are those who are hindered by the slightest rustle, and even the very fact that something rotates, moves, spins in the system unit. This guide is primarily addressed to such enthusiasts.

The cost of such a system is important. It will be an order of magnitude higher than a similar PC configuration with an active cooling system.

We select components
Usually, when choosing a processor, we look at the number of cores and threads, clock speed, study the results of performance tests and almost never look at heat dissipation. The maximum that it affects in ordinary life is the cost of the cooling system.

The assembly is not quite ordinary, and we will approach the choice from a different angle. Particular attention should be paid to TDP. The lower it is, the better. Ideally, we choose a processor with a declared heat pack of up to 65 watts. Although, given the energy efficiency of modern processors, you can choose almost any desktop option.

The choice of the motherboard in our case is actually not determined by anything. We select the motherboard according to the main characteristics. A massive chipset heatsink and VRM would be nice, but it’s not necessary.

There are no special requirements for the choice of RAM either. We choose as usual, by frequency, timings and chips. Well, the cost of course. Radiators will come in handy, but they are not a key feature for choosing RAM.

Storage device
When we say “storage”, we mean SSD, of course. Modern solid-state drives tend to heat up a little, and only with active reading / writing. Therefore, we choose according to our taste, volume, speed, pocket. The presence of a radiator is desirable.

video card
The choice of video card should be approached responsibly. After all, it is one of the main “heaters” of the internal space of the system unit. Just like when choosing a processor, you should pay attention to TPD. But, besides this, a cooling system is always “complete” with a video card. And for different manufacturers and even in different lines of the same manufacturer, the cooling of video cards built on the same GPU can vary greatly. And we are talking not only about the size and number of fans, but also about the number of heat pipes and the size of the radiators.

A clear demonstration of the difference in cooling systems for video cards built on the same GPU, using the example of Asus Dual GeForce RTX 2060 SUPER EVO OC (left) and Palit GeForce RTX 2060 Super Dual (right)

For our semi-passive system, more massive cooling would be preferable. After all, the larger the area of ​​​​the radiator, the more heat it can dissipate, even in passive mode.

Specifically, the following graphics card models are good choices (if you’ve settled on the RTX2060 Super):

Видеокарта GIGABYTE GeForce RTX 2060 Super GAMING OC [GV-N206SGAMING OC-8GD]

[PCI-E 3.0 8GB GDDR6 256bit 1470MHz – 1710MHz DisplayPort x3 HDMI]
133 31

Видеокарта ASUS Dual GeForce RTX 2060 SUPER EVO OC [DUAL-RTX2060S-O8G-EVO]

[PCI-E 3.0, 8 GB GDDR6, 256 bit – 1725 MHz, DVI-D, DisplayPort (2 pcs), HDMI (2 pcs)]
46 3
When choosing video cards based on other GPUs (for example, 1660 Super or RX 5500 XT), we rely on the same features – the massiveness of the cooling system.

One of the key points in building a computer with a semi-passive cooling system is the case. Inside it will be heat sources that need to be removed outside the system unit. Everyone knows perfectly well that warm air rises, and this must be taken into account.

Approximate air flow diagram using the Zalman S2 case as an example

An ideal case for our concept must necessarily have ventilation holes (seats for a case fan) on the top panel to bring heated air out. It would be desirable to perforate the bottom (and the PSU casing, if any) and / or the side wall to take cold air from outside. The front panel must be perforated and have seats for case fans. And in passive cooling mode, the ventilated front panel will also contribute to the air exchange.

Perforation and space for a fan on the top panel.
Perforation and space for a fan on the front panel.
Perforation of the bottom (and casing of the PSU).
Perforated left side cover.
The first two items are required. Points 3 and 4 are desirable.

If we talk about specific models of cases, then the following are quite suitable:

Cougar MX350 Mesh-X housing black

[Mid-Tower, Micro-ATX, Mini-ITX, Standard-ATX, USB 2.0 Type-A, USB 3.2 Gen1 Type-A]
2 699 *
692 38
In stores: in 236 stores

Housing ZALMAN S2 black

[Mid-Tower, Micro-ATX, Mini-ITX, Standard-ATX, USB 2.0 Type-A, USB 3.2 Gen1 Type-A]
3 599 *
251 31
In stores: in 2 stores
Case fans
Although our system is semi-passive, case fans are indispensable. With a high load, the amount of heat that needs to be removed outside the case also increases significantly.

When choosing case fans, keep in mind that the noise depends mainly on the fan speed. Therefore, when choosing a fan, attention should be paid to the minimum rotational speed and / or minimum operating voltage. The lower, the quieter.

Fan be quiet! PURE WINGS 2 [BL040]

[140 x 140 mm, 4-pin, 1000 rpm, 19.8 dB, 1 included]
1 150 *
443 9
In stores: in 93 stores

Fan Arctic Cooling P12 Silent [ACFAN00130A]

[120 x 120 mm, 3-pin, 1050 rpm – 1050 rpm, 28dB – 28dB, included – 1]
599 *
29 2
In stores: in 1 store
Modern motherboards are able to control the fan speed both by PWM (PWM) and by voltage (voltage). That is, now, in order to change the rotation speed, you do not necessarily need a fan connected with a 4-pin wire, a 3-pin is also suitable, which is usually also cheaper.

We choose the number of fans to taste. In general, one blower on the front panel and one exhaust on the rear panel will suffice.

Fan Splitter
Some motherboards only have two fan headers, one for the CPU and one for the case. In such cases, a splitter for connecting a fan will help out, which will make several from one connector.

Nanoxia NX34A30 fan power splitter

[material – metal/plastic, length 30 cm, for 4 fans]

Splitter DEEPCOOL FH-04

[4-pin (FAN) – 4-pin (FAN) x4, 550 мм]
450 *
1965 70
In stores: in 225 stores
Power Supply
Choosing a power supply for our tasks is not so easy. There are quite a few PSU models on the market that fully implement the semi-passive cooling mode. Some models do not turn on the fan only at 10-15% load, which, of course, is not enough. And only a few models can boast of a passive cooling mode at a load of up to 30-40%.

If we talk about specific models of power supplies in which the semi-passive cooling mode is adequately implemented, then these are the following:

Corsair HX750 Power Supply [CP-9020137-EU]

[750 Вт, 80+ Platinum, EPS12V, APFC, 24 pin, 4+4 pin x2 CPU, 8 SATA, 6+2 pin x4 PCI-E]
16 599 *
47 8
In stores: in 4 stores

Power Supply Corsair RMx 650W [CP-9020091-EU]

[650 Вт, 80+ Gold, EPS12V, APFC, 24 pin, 1x 4+4 pin CPU, 8 SATA, 4x 6+2 pin PCI-E]
48 6
Also on sale you can find power supplies with completely passive cooling. Of the minuses of such solutions, low power and high cost can be noted. There are few such BPs and you can count them on the fingers:

Power Supply Super Flower Golden Silent 500W [SF-500P14FG]

[500 Вт, 80+ Platinum, EPS12V, APFC, 20 + 4 pin, 4+4 pin CPU, 6 SATA, 6+2 pin x2, 6 pin x2 PCI-E]
15 999 *
12 4
In stores: tomorrow (from 10:00)

Power Supply Seasonic Platinum 400 Fanless [SS-400FL2]

[400 Вт, 80+ Platinum, EPS12V, APFC, 20+4 pin, 1x 4+4 pin CPU, 6 SATA, 1x 6+2 pin PCI-E]
17 1
Power supplies with a semi-passive cooling system should be installed at the bottom of the case (of course, the case must be of the appropriate design) with the fan up. This should be done so that warm air exits the power supply case in a natural way, rising up. This is also why the perforation of the PSU casing in the case is desirable.

Cooler CP
The processor cooling system for our semi-passive PC should have the maximum number and thickness of heat pipes, and a large dissipated area. To put it simply, the cooler should be large and heavy (preferably over 1 kg).

Approximate diagram of natural air convection through a CPU cooler heatsink using Scythe Ninja 5 (left) and be quiet! DARK ROCK SLIM (right)

The design of the radiator should be wide for better natural convection. It is desirable that the distance between the radiator plates should also be increased.

If we talk about specific models of coolers for the central processor, then you should pay attention to the models:

Scythe Ninja 5 CPU cooler [SCNJ-5000]

[base – copper, 800 rpm, 14.5 dB, 4-pin, 150 W]
7 199 *
31 14
In stores: in 3 stores

CPU cooler be quiet! SHADOWROCK 2 [BK013]

[base – copper, 1600 rpm, 25.4 dB, 4-pin, 180 W]
20 5
Setting the rotation speed of the CPU cooler and case fans
To adjust the fan speed, we will use the capabilities of the UEFI BIOS. Using the Gigabyte GA-A320M-S2H V2 as an example, we will analyze the process in detail.

First you need to enter the UEFI BIOS and find the Smart Fan 5 tab . Other motherboard manufacturers will refer to this feature differently. In any case, we will see a similar picture:

Find the Fan Speed ​​Control tab and select Manual .

Let’s set up the fan speed graph approximately as shown in the screenshot below. Before the processor temperature is below 50°C, the fans will not spin. You can set a higher value, for example 60 °C. It’s safe too. But a larger value should be set very carefully. And in general, if the whole body is sufficiently perforated, this should be enough. The fan will only turn on when the specified temperature is exceeded. The rotation speed will depend on the curve we have set up.

After setting, click “Apply” and select the fans for which you want to use this rotation speed scheme.

Sometimes the “Auto” fan control type does not work correctly even with 4-pin fans. In this case, you should change the CPU Fan control mode to Voltage .

We save the BIOS UEFI settings and restart the computer. After that, the case fans and CPU cooler will work according to our settings.

The settings on different motherboards and different versions of the UEFI BIOS will most likely be different, but the general logic will be the same.

Adjusting the speed of the fans of the video card
We will regulate the speed of rotation of the fans of the cooling system of the video card using the MSI Afterburner program . The utility is free and available for download on the official MSI website.

MSI Afterburner utility will work with graphics cards from any manufacturer, not just MSI

On the main screen of the utility, click on the gear icon and get into the settings.

Go to the “Cooler” tab and check the box next to “Enable software user auto mode” . A curve appears in front of us, similar to the one in the UEFI BIOS.

In the drop-down menu, change the cooler speed curve preset to “Arbitrary” . Adjust the curve, similar to the one in the screenshot above. The minimum fan start temperature should be set at 55–60 °C, the hysteresis is 5–10 °C. After that, click “Apply” and enjoy the silence.

A real example of a system with semi-passive cooling
As proof of the consistency of the statements contained in this article, consider a real system with semi-passive cooling, which is operated for 10–14 hours daily for six months.


Processor: AMD Ryzen 5 2400G,
CPU Cooler: Deepcool Redhat,
Motherboard: Gigabyte GA-A320M-S2H V2,
ОЗУ: Kingston HyperX 8 Gb x 2 (2666 Mhz 16-18-18-39),
Video card: Asus RX 580 4 Gb (Dual-RX580-O4G),
SSD: Western Digital SN550 250 Gb,
Корпус: Gamer Storm Macube 310P,
Case fan: 120 mm, exhaust on the back of the case,
Power supply: Corsair RM 650W,
Operating system: Windows 10 64-bit.
The system works absolutely silently. The fans do not spin, the air does not make noise. There are no moving parts. Of course, these statements are true for system operation at low load. Several Word and Excel documents are open at the same time, 20–25 tabs in the Chrome browser, Photoshop with periodic image editing (collage, correction, image clipping). In addition, Aida 64, MSI Afterburner and several other utilities are almost always hanging in the background.

The case fan and CPU cooler are configured in the BIOS and MSI Afterburner as shown in the screenshots above, in the corresponding section of the article. The rest of the settings in the BIOS and MSI Afterburner are left by default.

In the screenshot above, you can see the data on the temperature indicators of the system obtained after several hours of typical operation. Everything that could warm up warmed up, and the temperature stabilized. The picture can not be called ideal, but everything is within the normal range. The most heated GPU VRM is 62 ° C, and the GPU diode is 51 ° C. Next comes the VRM CPU – 59 ° C and SSD – 57 ° C. The processor temperature is low – 51 ° C, and the chipset is 40 ° C at all.

At the same time, the case is not the most ventilated (small slots at the end of the front panel and a completely blank PSU casing), even modest radiators are absent on the VRM, and the M.2 slot is located between the video card and the CPU cooler tower.

If the configuration is corrected as recommended in this article, the temperatures of this particular system will drop another 5-7°C.

For comparison, below is a screenshot with data obtained with active CPU cooling and one 120mm exhaust fan. The rotation speed is set to 30% in the UEFI BIOS. The graphics card fans are still not spinning.

Temperatures in this mode differ by an average of 8-10 ° C, which is not so much when it comes to values ​​that are far from critical.

Assembling a computer with semi-passive cooling is a doable task. Especially if you take the issue of building such a system seriously and thoroughly think through each component. Of the positive aspects, in addition to noiselessness at low loads, it is worth noting a significantly smaller amount of dust. In such a system, the fans turn on less often, the volume of air pumped is lower, and therefore there is less dust. Of course, there are also negative aspects, the main of which is the cost of building such systems, due to the specific approach to choosing some components.


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