windows 7 suspend2ram gets into hibernation after a while

[asasega]

Hi

If I put win7 into suspend2ram then after a while he goes into hibernation

Example

I suspend windows and resume after lets say 5 minutes, it's resume normally like from suspend2ram

But if I let the PC in suspend2ram for a longer period, let's say 1 hour, then when I wake the PC it's resuming from a hibernation

Why is that?

The PC is a desktop, not laptop

powercfg -a it gives me S3 type suspend

So I can enter and resume fine, just that after a longer period of suspend the PC wakes from a hibernation

I tried with Hybrid and not hybrid suspend