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    ROG Enthusiast Array EncodeGR PC Specs
    EncodeGR PC Specs
    MotherboardAsus ROG Maximus XIII Hero
    ProcessorIntel Core i7-11700K
    Memory (part number)Kingston HyperX Predator RGB 32GB (4x8GB) DDR4 3600MHz CL17 Memory Kit - Black (HX436C17PB4AK4/32)
    Graphics Card #1MSI GTX 1070Ti Gaming X 8GB
    Sound CardCreative Sound Blaster Z
    MonitorDell Ultrasharp U2520D 25" QHD IPS
    Storage #1Samsung 980 Pro M.2 Nvme PCIe 4.0, 500 GB
    Storage #2Samsung 970 Evo Plus M.2 Nvme PCIe 3.0, 1 TB
    CPU CoolerNoctua NH-U12A
    CasePhanteks Enthoo Evolv X Glass - Black
    Power SupplyAsus ROG Thor 850W Platinum
    Keyboard Logitech G915 TKL Lightspeed, Tactile
    Mouse Razer Basilisk V2
    Headset Sennheiser Game-Zero Headset
    Mouse Pad Asus ROG Sheath XL
    Headset/Speakers Logitech Z333 2.1 Speakers
    OS Windows 10 Pro 64-bit
    Accessory #1 Noctua NF-A14 PWM (x6)
    Accessory #2 Phanteks Halos Lux
    Accessory #3 Phanteks Neon Digital-Rgb

    Join Date
    Feb 2021

    Question Asus ROG Thor 850W - Swap Original Fan with Noctua

    The problem with ROG Thor 850W PSU is its fan noise. One week after i bought the PSU, the noise started. A very annoying bearing / motor noise when the 0-rpm is disabled, or when the load is high enough for the fans to start. The noise of the PSU is literally the only noise i can hear in my system right now... Dealing with RMA is not an option, especially during the covid period, as it's going to take too long and i already know it's going to be rejected anyway, with the typical response "it sounds as it should sound". No Asus, when you build a premium silent system and you pay that much money for a PSU it does NOT sound as it should.

    So, i've decided to not give a damn about the warranty and swap that cheapo fan anyway, with a quality one that will endure, making sure it meets the specs.

    I've found the specification for the original fan (Model: PLA13525B12M - shown in the screenshot below (curve 2) ).

    Click image for larger version. 

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    1. I know i will void the warranty.
    2. Yes it can be dangerous, but i can handle that kind of stuff and always take precautions.
    3. There will be some cable soldering with thermal heat shrinks, for the 3pin to 2-pin convertion.
    4. New holes need to be drilled on the fan, to match the 135mm metal bracket that holds the fan.


    The best candidate for replacement in my opinion, is the Noctua NF-A14 IndustrialPPC 2000 (3-pin). It's 12V, meets the curve of the original fan, and has pretty much the same airflow and better static pressure. Its minimum voltage seems to be 4.95V and it's running stable at 5V. I shouldn't have any problems at 5V and runs quieter at low rpm.

    My concern however is the starting voltage of the PSU for the fan. Most PSUs start with a higher voltage (say 7V), and after 1-2 sec drop it to 5V where it stabilizes, until higher rpm and thus voltage is needed. Some people have tried other fans on other PSUs, like the Noctua NF-A14 FLX, which have a minimum voltage of 5.5 - 6.0 V. As a result the fans would not keep spinning with a PSU voltage of 5V. That makes sense.

    There are PSUs however that drop the voltage below 5V, and that would cause a problem.
    Does anyone know what the PSU minimum voltage for the fan is ? Does it stabilize at 5V or drops lower ?
    Last edited by EncodeGR; 03-16-2021 at 11:02 AM. Reason: Final

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