You might try going to the laptop manufacturer's website and see if they have information on any models they produced that have the Sandy Bridge chipset problem. There were not very many laptops produced before Intel announced the problem and none were produced after that date with the faulty chipset. Most likely if you got your laptop after late April it will have the B3 chipset. The manufacturer's website probably has a way to determine if your laptop has the problem chipset. If they have a software application to check for the problem it will work since it was designed to work on all their laptops.
You might be able to find out with CPU-Z, a free program you can find here:
On the Mainboard tab the Chipset information will be displayed either on the Northbridge or the Southbridge line. You can see in the picture below that I have a P67 Rev. B3:
I say might, because I cannot predict that this program will be able to find the chipset data, if your laptop manufacture did not set things up appropriately.
When you refer to voiding your warranty on your laptop, do you mean opening the case to find the sspec printed on the chipset? If so, that is much more difficult and dangerous to accomplish than using the software methods, and once opened you may not be able to find the sspec number on the chip itself anyway. I would think that your laptop's manufacture has a method of identifying the chipset, by it's serial number or other identifier.