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What could cause a PC to wake up with blank screen, fan at full speed?

I have an HTPC build which uses the MSI G41TM-E43 motherboard with an Intel C2Q processor with 4GB RAM.

https://www.msi.com/Motherboard/support/G41TME43#down-manual

About a week ago, I noticed the HTPC fan was running at full speed. When I turn on the TV, there is nothing on display. I have to long press the power to shut it down. Then I noticed that it is happening more often when waking it up from sleep.

In the past, I have run into this issue if I put the HTPC to sleep and wake it up immediately (hitting HTPC remote by accident). But now it is happening more often without a short sleep. I have not run into this issue with cold boot. But since this is an HTPC, it needs to sleep/wake up to record TV.

Any ideas what could be the cause? Should I be looking into swapping the power supply first? Or should I swap the CPU?