The 8SIML motherboard is a standard Micro-ATX layout with 1 AGP 4x slot, 3 PCI slots and 1 CNR slot. This design is the base layout for the value motherboards today. Peripherally, even in the all onboard line having upgrade options are a must and this baby does just that. While supporting onboard AGP video, it also allows for AGP video cards to be installed thus shutting down the onboard video for you; much like I815 used to do.
Chipset, 645 with video
Powering the GA-8SIML is the SiS 650 value chipset. This is comprised of two parts, the 650 Northbridge and 961 Southbridge. SiS has described this as a SiS 645 with SiS 315 AGP 4x graphics built in. Lets see if that's true. As for the Southbridge, all is the same as the original 645.
For your networking and broadband needs (xDSL and Cable modems), Gigabyte has added the Realtek RL8001B Fast Ethernet controller chip. Based directly on the Realtek 8139 technology, it is designed as a small onboard LAN controller chip for OEM's. In real-world use, you will see no difference between the two chips.
The board itself does have some overclocking options but they are very sparse. You have your Standard Frequency/Voltage Control menu in the Award BIOS (personally I prefer Award to AMI, seems to have better IRQ routing). Under this menu you have your Auto-Detect DIMM/PCI CLK option and Spread Spectrum.
The first of the overclocking options is the FSB Clock. This is adjustable from 100MHz up to 200MHz in 1MHz steps, at least they got that part right. After that is the CPU Voltage Control. You can change the voltage from 1.1v up to 1.85v in 0.025v steps. Good voltage ranges but that's where it all stops. No AGP voltage, no Ratio selectors, nothing. This being said, we got a maximum of 113 MHz out of the FSB before the AGP card we used started to say "No way" to the higher AGP bus speeds. Unfortunately, due to today's video cards getting faster and faster, they need a more stable AGP bus. And to overclock it you need to be able to set the ratios manually. In all, very poor overclocking.
As for tweaking, the board does have all of the memory features including memory clock speeds of 100/133/166 for DDR-333 memory, so in a word excellent Intel alternative board.