Sadly the image and the gallery image aren't sharp enough to read the silk screen and the manual doesn't really indicate. Two possibilities I can see,
Bottom right above the I/O is the clear CMOS jumper, the 8-pin chip next to it may be the BIOS chip.
There is also an 8-pin chip quite near the battery and clock crystal that could also be the BIOS. Take a close look at the board and see if you can read the chip information. Looking that up should tell you if they are EEPROM or some other type of chip.
It is also possible it is under the heatsink somewhere.