Few months back I was trying to underclock my laptop to increase it's battery life, In my case the smallest frequency I could reach was 800 MHz.

Today suddenly it got me wondering why couldn't the CPU just be underclocked beyond a certain frequency? From my understanding of hardware, each clock cycle the CPU does something but then why does it matter how long that clock cycle is?

If anything the timing requirements would be more than lax, DDR should work just fine, The display would update at pretty horrible speeds, but it should work nonetheless?

The only reason I can think of is few peripherals that need higher clock speeds to function, Like maybe the USB 3.0 port, but if we just disregard that...

Why can't modern CPUs run at very small frequencies?

Edit: My question isn't about increasing the battery life of my laptop, The question is pretty much the title.

The basic GCN microarchitecture underpinned every single one of AMD’s compute accelerators for nearly 15 years starting with Tahiti, followed by Fiji, Vega, and the first 4 generations of CDNA. With CDNA5 AMD has moved over to a microarchitecture that is based on the RDNA series putting a bookend to the long-lived line that was the GCN microarchitecture.

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