Liquid Cooling a Dual RTX 5090 and Threadripper PC: Solving Overheating Issues for Peak Performance

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Initial PC Build and Overheating Problem [0:00]

The presenter showcases his "fastest PC ever built," featuring:

• Components:
  • Two RTX 5090 GPUs [0:04]
  • Latest 64-core Threadripper 9980X CPU [0:08]
  • 128 GB of RAM [0:08]
  • 2200W power supply to sustain the high power draw [0:12]
• Problem:
  • The top GPU was severely overheating, reaching 87°C after only a few minutes of rendering [0:17] [0:23].
  • This led to screaming fans and noticeable performance loss from the thermally throttled GPU [0:28] [0:31].

    

  • The presenter resolved to fix this issue by implementing a custom liquid cooling solution [0:35].

Disassembling the Threadripper CPU [0:46]

• CPU Details:
  • AMD Threadripper 9980X [0:48]
  • 64 cores, 128 threads [0:50]
• Cooling Requirement:
  • Surprisingly, the CPU doesn't require as much cooling as one might expect, especially out of the box [0:53].
• Water Block Installation:
  • A custom Heatkiller water block was chosen due to difficulty in finding compatible Threadripper blocks [1:00].
  • The block offered full coverage, a clean design, and straightforward mounting [1:07].

    

Disassembling the RTX 5090 GPUs [1:13]

• GPU Disassembly Process:

  • The presenter expressed regret over disassembling the GPUs due to the efficient two-slot cooler design on the new Founders Edition (FE) cards [1:16].
  • He emphasized careful disassembly to allow for potential reassembly with original coolers [1:22] [1:26].
  • Step-by-step removal:
    • 1. IO bracket and screws at the rear [1:32]
    • 2. Two more screws at the other end [1:39]
    • 3. Hourglass piece on the backplate (held by magnets, removed with a plastic scraper) [1:40]
    • 4. Four more screws securing side parts on the backplate [1:49]
    • 5. The PCIe connector, a separate piece on FE GPUs, secured by six screws and its own retention bracket. This part required extreme caution [1:55] [2:06].
    • 6. Four main screws clamping the GPU down to the heatsink, loosened carefully to ensure an even release [2:50].
    • 7. The retention bracket design (pre-bent, no springs) was noted for its unique tension-based mounting [3:00].
    • 8. Removing the fans, wrestling with the heatsink and its annoying clips, and then carefully detaching the IO connector (which carries all display data) after applying a bit of heat [3:59] [4:09].

         

• Insights into the 5090 FE PCB and Cooling [3:10]:

  • The bare GPU board revealed its extremely small and dense nature, with components packed closely [3:14] [3:17] [3:20].
  • The GPU die itself is massive, and GDDR7 memory is stacked almost overlapping [3:24] [3:26].
  • The board integrates dense power circuitry, leaving no extra room [3:31] [3:34].
  • This compact design is a key reason for the 5090 FE's effective air cooling, allowing unobstructed airflow through the heatsink [3:36] [3:42].
  • Liquid metal thermal interface further enhances thermal conductivity [3:46].
  • The 5090 die has a unique gasket system with three barriers to protect the liquid metal from degradation and spilling onto circuitry, which proved effective as the original liquid metal looked new [5:04] [5:08] [5:15].

    

Installing Water Blocks on GPUs [4:21]

• Water Block Aesthetics:
  • The GPUs were fitted with "Bixie" water blocks purchased from AliExpress [5:22] [5:24].
  • The presenter praised their aesthetic, preferring the workstation-focused design over typical gaming blocks with acrylic and RGB [5:39].
  • The water blocks are compact, single-slot, 234mm in length, with inlet/outlet ports at the end [4:46].
  • Half of the block is empty space, designed to accommodate the IO cable [4:51].

    

Case Change & Radiator Installation Challenges [5:37]

• Initial Case Issues [5:44]:

  • The original Phanteks case used for air cooling was not suitable for extreme liquid cooling [5:44] [6:07].
  • 360mm radiators barely fit, and proper bottom mounting was impossible, disrupting the planned "dense and insane" cooling setup [5:51] [5:56].

    

• New Case Selection (McPro Apollo X) [6:16]:

  • The presenter switched to the Apollo X case from McPro, which he had reserved for an "epic" build [6:23] [6:30].
  • The case is a high-quality Mac Pro clone, replicating the design, anodizing, and CNC-milled "cheese grater" front panel very closely [6:35] [6:42] [6:46].
  • Despite being more compact than the previous case, it accommodates the EATX Threadripper motherboard without issues [7:00] [7:06].

    

• Radiator and Fan Setup [7:23]:

  • Measurements confirmed ample space for radiator volume [7:18].
  • Front Radiator: An Alphacool 360mm radiator, 86mm thick (equivalent to three standard AIO radiators), was installed. Its low fin density suggests optimal performance with push-pull fan configurations at lower speeds [7:25] [7:31] [7:39].
  • Fans: Arctic P12 Pros were chosen for their airflow and low noise [7:48]. Slim fans were necessary on the rear of the front radiator to prevent blocking the motherboard's 24-pin connector [8:07] [8:11].
  • Bottom Radiator: A 240mm radiator was installed at the bottom, though a thinner model was required due to GPU clearance [8:20] [8:24].
  • Exhaust Fans: Two 80mm Noctua fans were added to the rear for extra exhaust to support the 5090s [8:32] [8:36].

    

Custom Pump/Reservoir Mounting Solution [8:48]

• Pump and Reservoir Selection:

  • A UNI240D pump/reservoir from Steel Key with an Apex D5 pump from Alphacool was selected [8:53].
  • This unit acts as a pump, distribution block, and coolant reservoir [9:00].

    

• 3D Scanning and Design [9:09]:

  • Due to extremely limited space (5mm clearance on either side of the motherboard area), the presenter 3D scanned the case interior to create a precise 3D model in Fusion 360 [9:11] [9:17] [9:31].
  • The goal was a hidden, clean, and toolless mounting solution, as the pump/res mounting points were on its back [9:45] [9:47] [9:51].

    

• 3D Printing the Mount [10:09]:

  • A sliding rail design with a self-locking notch was developed in Fusion 360 [9:58] [10:00].
  • The mount was 3D printed in resin on a Formlabs Form 4 due to its speed and high tolerance requirements for sliding parts [10:11] [10:18].
  • After one reprint for perfect alignment and thickness adjustments, the mount successfully integrated the pump/res into the top part of the build [10:28] [10:30] [10:33].
  • This design allows for easy, toolless removal to access RAM or CPU [10:37] [10:42].

    

Final Assembly and Performance Results [10:44]

• Liquid Cooling Installation [10:44]:

  • The 5090 GPUs were dropped in, tubing connected, and the loop filled with coolant [10:45] [10:48].
  • The final build presented a sleek, minimalist aesthetic with the complex liquid cooling hidden beneath the surface.

    

• Temperature and Performance Improvement [12:03]:

  • The liquid cooling system dramatically improved GPU temperatures.
  • Under full load in Blender, both 5090 GPUs now run below 50°C [12:28] [12:30].
  • Even with side panels on, reduced fan speeds, and the Threadripper also rendering, GPUs stayed below 60°C at an ambient temperature of 24°C [12:38] [12:41] [12:43].
  • This is a significant improvement from the air-cooled setup where the top GPU hit 87°C [12:20].
  • The cooler operation led to increased performance:
    • Boost clocks increased by almost 200 MHz [12:56] [12:57].
    • Power draw was reduced to around 400W in Blender (compared to 575-600W out of the box for air-cooled cards) and 450W in V-Ray [12:59] [13:12] [13:18].

      

• Comparison to Mac Pro [13:38]:

  • The presenter highlighted that the PC's performance, particularly in GPU compute for rendering and gaming, is vastly superior to a fully specced Apple Mac Pro [13:40] [13:43] [13:54].
  • He acknowledged MacBooks and Mac Minis but emphasized Apple's lag in enthusiast-level GPU compute [13:49] [13:52].
  • The finished machine offers extreme performance in an aesthetically pleasing, "different planet" looking build [13:36] [13:38] [14:00].