Quiet Liquid Cooled Gaming PC Build Guide

Do-It-Yourself Systems | Silent PC Build Guides
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THERMAL & ACOUSTIC PERFORMANCE

Config #1: Radiator Fans at Full Speed

To begin, let's check system temperatures and noise with the radiator fans at full blast, and the pump at 100% speed. The front fan is at 600 RPM, the back fan at 720. Furmark is running at maximum stress/power level, and the CPU is stressed Prime95x4 on torture test. Room temperature was around 21°C when this test started, and idle temperatures of both CPU and GPU were absurdly low, near ambient.

All the temperature sensors started rising when the tests loads were applied, but slowly. In fact, it took the better part of an hour for temperature to stabilize. AC power draw began at about 435W and slowly climbed with temperature to 445W maximum. Given the 92%+ efficiency of the Corsair HX850i PSU, this translates to ~410W DC. The PSU fan may or may not have been running; it was simply not audible as a discrete source. The image capture from AIDA64 below shows all the temperature sensor details, but to summarize, the CPU hit 55°C, and the GPU reached 51°C. By then the room was about 3~4°C hotter, so the temperature rise was just 30°C and 26°C.

You have to remember that our test load is a constant high load, higher than any game can reach (by a margin of at least 10%, according to many sources and by our own experience). Even the most demanding computer games don't demand unvarying power, as the power demand goes up and down depending on the action, and even the skill of the player(s). What this tells us is that under actual use loads, this system will never see the kind of temperatures reported here, for any of the fan/pump speed settings. (Assuming your room temperatures are not typical of subtropical summer.)


The SPL of the system with the radiator fans at full speed is 34 [email protected] SPCR regulars would not call this quiet but many mainstream PC gamers would consider it perfectly OK. Temperatures are amazingly low.

Best Low Noise Configuration

It took most of a whole day of iterative adjustments, and another couple of vent grill/fan mods, but I finally managed to get the overall noise way down with a smooth acoustic signature, and still keep component temperatures to modest levels. After 51 minutes of extreme system load, both CPU and GPU sensors stabilized at 66°C and the measured SPL was just 18 [email protected]


Just 18 [email protected] SPL for a 445W system with GPU and CPU temperatures at only 66°C!

To achieve this result, the pump was set to 35%, the three 120mm radiator fans were dialed down to 660 RPM, the back fan to 500 RPM, and the front fan to just 330 RPM. The front fan doesn't always start immediately at this speed but usually comes to life within a minute or so. It's not a critical fan; turning it off all together didn't raise temperatures by more than a few degrees. To be safe, it is better set to around 380 RPM. Any increase in noise is under 1 dBA and virtually inaudible.

Then there are the vent grill mods. These were part and parcel of the work done to achieve the final results above.

MORE FUN WITH GRILLS & DUST FILTERS

I made a few comments earlier about the mutiple layer airflow impedances on the vent openings. The one that bothered most me was the top grill/vent. It has three layers, including a fine vinyl bug-screen type middle layer, completely unnecessary as this is an exhaust vent. If you read my article Quiet MicroATX Gamer #1, you'll remember that the cooling/noise challenge of the Corsair 240 Air case used for that build was solved eventually by the removal of dust filters. I decided to examine what effect the top vent grill of the Enthoo Luxe has on airflow.

First, I measured the airflow from the front top fan set at full speed, with the grill cover on: 190 feet per minute. Then I popped the grill off and repeated the test, taking care to position the anenometer vane at the same point and distance from the fan: 460 feet per minute. Wow! That's 2.4 times more airflow without the grill. Now, if you're a regular at SPCR you know that we don't take much stock in airflow, it's a misleading specification, much like horsepower by itself for engines. The relationship between cooling effectiveness and airflow is far from linear. But still, a 2.4 times difference is too much to ignore. So, off came the bug screen filter.


Our Kanomax 6803 Anemometer is an expensive ($845 today) precision instrument able to read as little as 40 FPM air velocity to as high as 7800 FPM with 1% accuracy.


The "bug screen" dust filter is thin and flexible, so I grabbed a portion with my fingers and pulled the whole thing out in one piece through one of the hex holes without cutting or changing anything else.

Without the dust filter in the grill, air speed improved to 270 FPM. That's much better than 190 FPM, but still a long way from 460 FPM. So the metal grill had to go. This was slightly more work: Some tabs had to be bent back. Off came the steel perforated grill. All that's left is the plastic inner frame with its elongated hex holes. With that plastic "grill", air speed went up to 400 FPM. A loss of 60 FPM seems acceptable... and the hex grill does offer a bit of protection for the fans.

This change to the top vent grill improved cooling by at least 5°C — the improvement varied a bit with fan speed. It is an essential part of the system tuning that allowed the best low noise config acoustic/thermal results reported above.


Final state of top grill for optimal noise/cooling.

Finally, I removed the dust filter from the front panel. This improved airflow through the front by at least 25%. Yes, it is an intake, and if the system resides on the floor, then you'll probably want to keep this dust filter on, speed up the fan a touch and clean the filter often.



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