Here we see Intel uses a 1/6/1 (AGP/PCI/Riser) expansion configuration. This is the typical layout for the new Intel motherboards, as i845G supports up to 6 PCI masters, so there are no reasons for not having 6 on i845G boards. Like all of Intel's P4 chipsets, the i845G supports AGP 1.5v cards only, so AGP 2x and 1x cards are not usable in this chipset. It is not a recommendation, it is a requirement. The CNR riser slot is placed onboard for OEM's and integrated users who need cheaper hardware options. Its not really useful to hardcore users.
i845G, the new brains behind Intel's brawn
Here we get a look at the i845G and its new ICH4 Southbridge. As you can see, the Northbridge looks totally identical to the i845 with only a very tiny G being added to the name. Due to our camera not being able to get close enough, you can't really see it but its there.
The biggest addition is the new ICH4. Intel's ICH4 is identifiable by the new prefix FW82801DB located on the chip. This chip also is 2 times the size of the ICH2 chip making it totally recognizable. ICH4 uses the same ATA-100 IDE controller and same speed Hub link as the ICH2, but that is where the similarities stop. ICH4 has upgraded its support for USB, adding an extra controller (3 total) for 6 ports. These ports are all USB 2.0 also. Yes, that's right, Intel is the first to release commercially available USB 2.0 on a Southbridge. Upgraded AC'97 sound has been added, rev 2.2 is used rather than 2.1. 2.2 states that the AC'97 audio must produce 6ch audio, so you can have 5.1 speakers on a budget.
Intel Extreme Graphics, The extras for it
As we mentioned before, the Intel i845G comes equipped with onboard graphics built into the Northbridge chipset. This uses SMA (Share Memory Architecture) design where it uses system memory for the AGP. This allows you to use the board without having to have a graphics card installed. The card pictured above is a DVI, S-Video and RCA expansion card. If you are using the onboard graphics and have a DVI monitor or want to use the TV out system, you plug this card into the AGP slot and bingo, onboard graphics detects TV out and DVI. You now have full digital connections.
Here we get a look at the backplane for the i845G reference board. You will notice four USB ports on the back, and these are all USB 2.0 ports. On the board in the lower right hand corner is a standard Intel Pin header for an extra two USB ports for front panel connection. This gives you the full 6 ports with up to 480mbps transfer. Hooray for USB2!