PC crashing and locking up after installing Deepcool LS520 AIO

Hey everyone,

I’m dealing with a super frustrating issue. A few days ago I swapped out my CPU cooler for a Deepcool LS520 SE 240mm AIO, and ever since then my PC has been acting up.

The system will randomly hard-crash – sometimes during gaming or stress tests, but also completely at idle when I’m just on the desktop. What happens is weird: the fans and LEDs stay on, but the PC is completely frozen. It won’t respond to the power button at all, and the only way to recover is to flip the PSU switch (0/1) and drain all the power before I can boot again.

The build is a Ryzen 7 5800X on a Gigabyte B550 AORUS Elite V2 with 32 GB of DDR4, an MSI RX 6750 XT Gaming Trio, Samsung 980 NVMe + Seagate HDD, and an MSI MPG A850GF PSU. Temps are fine on both CPU and GPU, so it doesn’t look thermal. The thing is, this never happened with my old cooler – it only started right after installing the Deepcool AIO.

I’ve already tried updating everything, testing undervolt/power limit on the GPU, running 3DMark and OCCT… the crashes still happen. RAM tests clean, drives are healthy, nothing obvious.

So I’m stuck wondering: is this related to the AIO itself (pump drawing power, wiring, maybe I mounted it wrong)? Or is it just bad timing and my PSU is tripping out because of transient spikes from the 5800X + 6750 XT? I’ve seen some people mention issues with the MSI MPG GF series latching under load, which matches my symptoms.

If anyone has run into something similar – random idle + load crashes that require flipping the PSU switch – I’d love to hear your thoughts. Should I reseat the cooler and try different fan/pump headers, or just bite the bullet and test with a better PSU (Corsair RMx / Seasonic / BeQuiet)?

Thanks a lot, I’m losing my mind chasing this.