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New PC - upgrade, part 2



My EVGA GeForce RTX 3080 XC3 Hydro Copper 12GB arrived yesterday - and it looks perfect.  (It's also heavy.)  But unlike a normal air cooled graphics card I can't just drop it into my system.  I need to order a whole bunch of parts first.  Any water cooling loop will have the following:

  1. Blocks which attach to the CPU or GPU and transfer heat from the CPU or GPU to the coolant.  This is built into the graphics card, but I might as well get one for the CPU too (in for a penny...).
  2. Radiators which transfer heat from the coolant to the air.  While thicker radiators or ones with more fins will cool better (while requiring more powerful fans) cooling is mostly dictated by the area of the radiators.
  3. Fans to push (and/or pull) air through the radiators.  Ideally you want to use fans which have high static pressure as the radiators have high air resistance.
  4. A pump to move the coolant from the blocks to the radiators.
  5. A reservoir to hold extra coolant so the pump isn't sucking air.  The reservoir and the pump can be a combo unit.
  6. Tubing and fittings to connect everything together.


It's possible to buy an All-In-One (aka AIO) unit where the pump is integrated into the CPU block and the tubing between the CPU block and the radiator is permanently connected and pre-filled with coolant.  These are often significantly cheaper than a custom loop, but there's no easy way to adapt an AIO to cool my graphics card.


My original plan was to use a 180mm x 180mm radiator and the existing 200mm case fan.  However, the nice folks on r/watercooling advised against that plan.  The current rule of thumb is to have at least a 120mm fan+radiator per 100 Watts of power/heat.  So while the 180x180 radiator is 2.25 120mm equivalents that's not enough (even without a CPU block) because a 3800 can reach over 300W (!).


What else isn't enough is my 500W power supply.  While this is an additional expense, I suspected the power supply was another source of noise.  So I did some research and settled on the Corsair RM850X, it's supposed to be quiet and 850W should be sufficient.


But given I needed to maximize the radiator area I took the sides off of the case and did some measuring.  Unfortunately I couldn't simply stick two 240x120mm radiators in the top as i have installed the glass panel there (to avoid gravity & feline related issues).  And while the manual shows installing a 240x120mm radiator on each side, they would likely impinge on the motherboard.  Instead I decided to go with a 240x120mm radiator in the bottom of the case (where there is a fan grill), and three 120x120mm radiators - one in the rear and one on each side but towards the front so the motherboard isn't in the way.  The 120 rads are crossflow so the tubing basically makes a loop around the inside of the case and doesn't cross in front of the fans.


As I am Canada, my choice of retailers is fairly limited.  Dazmode is the main retailer for watercooling gear in Canada.  Fortunately they have a good selection and the house brand items are competitively priced, although a lot of the "name" stuff is pricy.  But I ended up ordering the following (Canadian dollars, tax & shipping included):


C$ 76.53 240x120mm radiator

C$133.62 3 120x120mm cross-flow radiators

C$ 27.36 8' EK-Tube ZMT Matte Black 3/8"-5/8" tubing (the cool kids use hard tubes, but I'm about function not looks)

C$111.20 15 compression fittings these connect the tubes to the G 1/4 inlets on each component, 2 for each component plus one for a drain tube

C$ 45.47 5 90 adapters, I plan on using these to handle any connections which require a tight turn

C$ 38.88 T fitting & drain valve - you should replace the coolant once a year, having a drain valve makes it easier

C$101.68 HEATKILLER IV BASIC CPU BLOCK with a clear acrylic top so I can see the coolant

C$ 20.57 Arctic Clean Kit & Thermal Grizzly Kryonaut Thermal Paste

C$233.17 Corsair XD5 Pump + Reservoir Combo

C$ 69.94 5 Arctic Cooling P12 PWM PST 120mm fans

C$ 26.80 1L Corsair XL8 coolant

C$203.39 Corsair RM850X power supply


Parts Total: C$1,084.61

Graphics Card: C$1,490.00

Grand Total: C$2,574.61


All I can say is I really hope this makes my PC quiet as the upgrade (and I'm not even upgrading the CPU, that would be another C$400-500) is costing as much as the PC!


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Counterpoint! I'm continually amazed at the intricacies involved in fluidic heat dissipation. But it's utterly & totally not for me.


Open, airy, light and breezy, simple PCs running on air cooling are epitome of elegance. Relying on process node shrinks and undervolting is foundational. Low-speed large 500RPM fans and "full-sized" heatsinks are stress-free and low-complexity. But at a performance penalty of maybe 15-20%. I don't worry about the difference since new tech is always right around the corner.

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The liquid coolant doesn't dissipate heat - it just moves it from the heat source to the radiators where it is then transferred to the air moving through the radiators.


Case fans are great for ensuring the air inside the case is room temperature, but unless you're using a completely passive heatsink, they don't actually keep the CPU or GPU cool. 


Modern CPU coolers use "heat pipes" to move the heat from the CPU cover to large radiators with fans.  Unfortunately graphics cards are significantly more space constrained with most graphics cards being smaller than a typical 240x120mm radiator - and in that space they must include the fans, heatsink, chips and PCB!  My RTX 3080 can generate over 300W of heat and even my GTX 1650 Super can generate 100 Watts of heat.  In order to dissipate that heat the 100mm fans need to move a lot of air over relatively small heatsinks (which aren't flow-through like a radiator, so even more static pressure is needed).  This results in very loud fans.


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On 5/4/2022 at 7:26 PM, EricBall said:

The liquid coolant doesn't dissipate heat - it just moves it from the heat source to the radiators where it is then transferred to the air moving through the radiators.

I like arguing that it's unnecessarily complex because of a pump and fluid that has to be compatible with materials. The liquid coolant transfers heat to radiators to where it is transferred to room/case temperature air. No different than heat pipes or vapor chamber. They all radiate to room temperature air.


Still a form of passive cooling, until you get into Peltiers or something with compressible refrigerant.

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