|Your mboard cannot use 4gb modules !|
If your Windows 7 version is 32 bit.....
see the last part of response 2. You are probably better off installing max 3gb rather than 4gb.
Note that if you mix modules that have different max speeds, the bios, at max, will run all the modules at the slowset max specs of all the modules.
I searched the web using: FoxConn 2A8Ch
.....and found this...
Hewlett-Packard Compaq 500B Microtower
"Model Hewlett-Packard Compaq 500B Microtower
Motherboard FOXCONN 2A8Ch "
It's an OEM only mboard model !
I searched the Kingston web site with: HP/Compaq and 500B....
Search Results for: HP/Compaq Business Desktop 500B Microtower
KTH9600B/1G 1GB 1333MHz Module
KTH9600B/2G 2GB 1333MHz Module
Standard Memory: 1 GB (Removable) or
2 GB (Removable) or
3 GB (Removable)
(the memory the model came with)
Maximum Memory: 4 GB
Expansion: 2 Sockets
Configurations up to 4GB can be reached using Kingston's 1 and 2GB modules.
NOTE that they list brand name system specific part numbers.
Local places probably won't have those part numbers but places on the web might.
If you don't want to fuss with finding brand name system specfic ram part numbers, don't buy Kingston ram. If Kingston, or any brand, does not list the module part number of ram you bought or were thinking of buying, then there's no way of knowing if it will work in your mboard - it may work fine anyway, but it may NOT !
Other ram manufacturer's or ram distributor's web sites where you can look up which modules you can use in your brand name system model, such as the Crucial web site, do NOT use brand name system specfic ram part numbers.
Once you know which module part numbers work in your model, you can search using the part number and buy the ram from anywhere you like that has it.