SIV is an extremely comprehensive system information tool that tells you everything you could ever want to know about your PC.
To take an example, when you launch the program you'll see a button called Volumes, and so you might think this would lead to a screen that lists your PCs drives, their free space and so on.
What you actually get is much, much more. Like pointers to your various drive types, manufacturers, serial numbers and controllers. There's geometry data (the number of cylinders, tracks, sectors and more). Information on partition layouts. And live file system statistics, so you can see which drives are being accessed the most.
There are specific reports on your USB and SCSI drives. Low-level Windows data like volume GUID names. Real-time SMART drive monitoring, so for instance you can see the current temperature of any SMART-compatible drives. Oh, and of course if you just want to know the capacity and free space of your various drives, then that's available too.
SIV offers the same in-depth reports on other areas of your hardware - the CPU, RAM, GPU, system buses, and a whole lot more.
The program also provides detailed network information, and troubleshooting tools.
And the Windows section is something like a supercharged Task Manager, telling you all about drivers, services and running processes, memory use, paging, loaded DLLs, security privileges and more.
The program's interface is a little odd, and there's so much available here that it can take a while to pick out the data you need. But there are few better ways to explore the technicalities of your PC, and others you might encounter, especially as SIV is portable and supports every version of Windows from 95 upwards (the server editions, too).