My Intel Motherboard DG43NB is showing ICH 75C at idle time and increases during load is it normal or getting overheating and if I am updating my BIOS whether my Warranty will get void or not.
You will see that from the link below the ICH temperature can go up to 97 under bias.
Anyway, you are free to update the bios without any fear of voiding the warranty
There are different ways of upgrading BIOS:
I prefer the BIOS recovery method as it always works. (ISO and Iflash are good as well.)
All the best,