I've had two TiVo boxes, both make an incessant drumming sound. The first technician replaced the box, second technician told me the noise is normal and the call centre tell me the box should be silent. My sisters is silent - I can't get any sense out of anyone at virgin, SHOULD the box make noise or not? It's driving me mad.
Welcome to the Community, I'm sorry to learn about the trouble you've experienced lately.
The TiVo box isn't going to be completely silent, although we wouldn't expect the noise to come from it to interrupt your viewing, so if that's the case then we'll look to why it's happening.
As you've had the issue with more than one set top box, it could be where the box is placed? Do you have anything to use a feet for the box if it's on a hard surface? Was the drumming sound the same on both set top boxes?