Enthusiast Moves PC Cooling Radiator Outdoors, Reduces RTX 4070 Ti Super Temperature to 34 °C

A Reddit user with the nickname Motor_Attention1865 developed a custom liquid cooling system for a computer that dissipates a significant portion of the generated heat outside the room. To achieve this, they installed an additional radiator on the exterior wall of the house and created an automatic system for regulating the coolant temperature.

The project took about two months. According to the developer, the idea arose due to the intense heat in the room during gaming sessions. With an outside temperature of −4 °C, they decided to use the cold air to cool a computer equipped with an NVIDIA GeForce RTX 4070 Ti Super graphics card.

The main technical challenge was the risk of condensation. If the coolant returns to the computer too cold, moisture from the room air can condense on the surface of components, causing a short circuit.

How the Cooling System with an Outdoor Radiator Works

The developer placed an Alphacool XE240 radiator with two Noctua iPPC-3000 fans outside the building, approximately four meters above the ground. An additional D5 pump circulates the coolant through the external loop.

A motorized three-way valve is used to regulate the flow. It determines which portion of the liquid passes through the outdoor radiator and which returns to the main loop without additional cooling. The system is controlled by an Arduino Mega microcontroller, receiving data from six sensors. Three of them measure the liquid temperature, while the other three monitor the temperature and humidity inside the case and in the room.

After Windows starts, control is taken over by a Python program linked with HWiNFO and FanControl. It calculates the dew point and adjusts the cooling so that the liquid temperature entering the computer remains 10 °C above this value. During testing, the margin is reduced to 5 °C.

In case of a program failure or loss of connection, the external loop automatically shuts down. To protect the liquid from freezing, the developer added ethylene glycol, lowering the declared freezing point of the mixture from −18 to −28 °C.

What Temperatures the Computer Showed

The system was tested with a GeForce RTX 4070 Ti Super graphics card and an Intel Core Ultra 7 270K Plus processor.

To increase the allowable power consumption of the graphics card, the author performed a shunt modification. After this, the sensors began to underestimate the actual power consumption by about 30%, allowing standard limits to be bypassed. According to the developer, under maximum load, the graphics card's power consumption reached 510 W, and the GPU frequency was 3,165 MHz.

In the Steel Nomad test, the graphics card scored 6,626 points at a temperature of about 48 °C. In Unigine Heaven, the temperature was approximately 37 °C, and after an hour of playing Counter-Strike 2, it was 34 °C.

The Core Ultra 7 270K Plus processor was also modified: its heat spreader was removed to improve heat dissipation. In the Cinebench R23 test, its temperature reached 52 °C. According to the owner, the system helped solve the initial problem of room overheating. However, the results were obtained on an individual configuration and have not been confirmed by independent tests.

Assembly Faced Leaks and Malfunctions

During development, the enthusiast encountered several technical issues. Due to the absence of a check valve, the system initially operated unstably, and a short circuit occurred on the custom control board between two transistors. Several more hours were required to find a fault, which turned out to be a damaged solder joint.

The most serious problem arose during the first filling of the external loop. The developer forgot to close the top of the reservoir, causing the coolant to spill inside the computer.

During assembly, the author also considered a simpler design with two independent loops and a heat exchanger between them. This approach would have allowed the internal and external parts of the system to be separated, but they decided to complete the initial project.

In the comments, users also noted potential issues with moisture, corrosion, and radiator operation in the summer. The owner acknowledged that the design would likely need to be modified in warmer weather. So far, the system has only demonstrated results in cold weather conditions. The developer has not provided data on its reliability during extended use and effectiveness in the summer.