The AsRock P4I45GV revision 5.0 motherboard uses an Intel 845GV motherboard chipset.
There is one AGP slot on the motherboard, used for a graphics card.http://www.asrock.com/MB/overview.asp?Model=P4i45GV%20R5.0
2) Information on the Intel 845GV chipset,http://en.wikipedia.org/wiki/List_of_intel_chipsets#Pentium_4_chipsets
Looking down the column on the left side until we come to - 845GV, and looking across, we see under the heading Graphics that Integrated Graphics is supported. No mention of AGP support.
But AsRock has implemented it's own technology of A.G.I. at an 8x speed.
(For the Intel 845GV chipset)
AsRock Graphic Interface,http://www.asrockamerica.com/AGI8x.htm
This means that graphics cards that use the AGP 8X technology, or AGP 4X technology, can be used. (AGP4X/8X)
Advanced Graphics Port,http://en.wikipedia.org/wiki/AGP
Using Sapphire's version of the ATI Radeon 6850 as an example, we can see this graphics card uses the newer technology - PCI-Expresshttp://www.newegg.com/Product/Product.aspx?Item=N82E16814102908
(Doesn't natter WHO makes it, the graphics card is still based on the ATI G.P.U.
Graphics Processing Unit. Or in slang terminology; the graphics chipset)
It also uses the newest version of PCI-Express, the PCI-Express 3.0 technology.
Information on PCI-Express,http://en.wikipedia.org/wiki/PCI_Express
Short answer to your question?
Your AsRock motherboard is set up to support AGP graphics cards that use either the AGP 4X technology, or AGP 8X technology.
Does not support graphics cards based on the PCI-Express technology.
For additional questions please post in a Comment.