Corsair 4000X & 4000D Review: An Excellent 450D Successor

For thermal and acoustic testing, we are using the following software and settings: 

Fan Characteristics 

The 4000X RGB’s 120mm spinners are PWM controlled, and they can run as low as 230 RPM in our sample. This is so slow, you can actually see them move during normal desktop use, which creates quite a neat effect with the RGB lighting. At top speed they’ll run at 1350 RPM, where they create a nice smooth sound that isn’t bothersome at all.

The fans in the 4000D Airflow are two 120 mm spinners controlled through adjusting voltages rather than with PWM signals, giving them slightly faster speeds on the low end. Nevertheless, they run at about 550 RPM at the lowest, which is still fine. At full speed they spin at about 1300 RPM. This isn’t fast, but should be adequate with the perforated front panel.

Acoustic Results

For our acoustic tests, we run three scenarios: CPU full load, CPU and GPU full load, and an optimized idle. The CPU Full Load test runs the CPU and case fans at their maximum speed. For the CPU and GPU full load acoustic test we add the Nvidia RTX 2070 Super FE at 75% fan speed, because in practice it never runs at 100 percent and is far too loud when it does.

For the optimized idle, we run the GPU fan speed at 40 percent (the 2070 Super FE GPU does not have a Zero-RPM mode), and run the CPU and included case fans at the lowest speed they will spin at.

Surprisingly, the Corsair 4000D Airflow was the quietest case we’ve had on this test bed – when measuring without the GPU. That’s because it only comes with two fans that don’t spin very fast. The 4000X RGB is a little louder, but still well within reason.

Thermal Results

For the thermal tests, all case and CPU fan speeds are set to 100 percent. The i9-9900K is pegged at a 4.6GHz clock at 1.1v on all cores to ensure consistent power consumption across test scenarios, and letting the GPU run at 75 percent fan speed enables it to maintain its power target while maintaining one set reasonable fan speed, so that the temperature is the only variable. 

Note that the 4000X RGB has a relatively high CPU temperature, but a low GPU temp. This is down to the lavish intake 3 fans) providing the GPU with fresh air, but the CPU suffers a little due to a lack of exhaust. Do yourself a favor and add an exhaust fan if you want good CPU temperatures (and a complete look), or use an AIO.

The 4000D Airflow performs like most mesh cases: great. It might only have two fans, but it’s able to use them effectively to provide enough cooling to both the CPU and GPU.

Standardized Results

To correct for differences in case fans, for the standardized test we remove the standard case fans and replace them with Corsair ML120 or ML140 units. Up to three fans may be installed, preferably one at the default exhaust location and two at the front intake, in the biggest sizes the case supports. The above tests are then repeated, but because the Corsair ML fans have absurdly high maximum speeds, we run those at 50% duty for the tests as no case fan should ever need to run above those speeds. 

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The standardized tests clearly show what each of the cases are built for. The 4000X RGB is the warmest running case in our standardized test suite, but it’s also among the first to have a closed glass front panel. Similarly, it’s also nearly the quietest, so the restriction provided by the glass panel at the front does do something to keep the noise down. 

But truth be told, if you’re looking at the 4000X RGB, you’re probably planning to use the included fans, and you’re probably looking at using an all-in-one liquid cooler for your CPU anyway.

The 4000D Airflow behaves like any mesh case does, trading blows with the likes of the Phanteks P500A.

Conclusion

If you were a fan of the original Corsair 350D or 450D, then you’ll like the new 4000 series cases. Or, if you’re a new builder looking to set up a gaming rig with one of Nvidia’s brand-new cards, there’s plenty to like here too. My pick goes to the 4000X RGB, which although it carries a $40 premium over the 4000D and 4000D airflow, comes with one additional fan, controls them via PWM instead of voltage-controlled, adds some classy RGB, and you get a very pretty glass slab – the 4000X RGB does enough things right to justify its premium.

Corsair’s RGB implementation is second to none. It doesn’t work with your motherboard’s ecosystem, which might at first be a bit of a let-down, but the way Corsair is able to control the lighting effects individually per-fan is brilliant and creates some very elegant effects, especially through the very fine mesh filter and dark-tinted glass panel. I never thought I’d say it, but this is some classy RGB. 

There’s definitely a bit of Corsair tax going on here, but it’s no more than maybe $10 when you compare these cases to competitors, which personally I think is well worth it for the clean styling and thoughtful design. Whether you opt for the 4000D Airflow or the 4000X RGB, you’ll be happy. But if you can swing the $40 for the RGB variant and don’t mind the slightly worse thermals (which are still generally good), we highly doubt you’ll regret your purchase. In my book, the 4000X RGB is the go-to mid-range RGB case of 2020, earning a spot on our Best PC Cases list.