You check your manual for your desktop or the motherboard manual.
It's limited by your motherboard on what CPU it can take. The list of supported processors is most likely listed in the manual.
Different jumper settings on a motherboard connect different circuits and processes. Check the motherboard documentation to see which jumper setting is correct for your application. Use caution, because incorrect jumper settings may harm the motherboard.
Yes. loimited by Motherboard chipset - check out the specs for your mobo at Tom's hardware or similar site.
Hertz, Don't it.
Yes, as long as there is an unused PCI slot on the motherboard - usually there are several and often white in color. Also, read the controller's box to ensure your operating system is supported before buying.
If you are referring to the speed of the RAM, then yes, you should check it before you buy it. For instance, the motherboard that you are using may be incompatable with the RAM you intend on purchasing, and as such, will not work.
I'm assuming you mean the Front Side Bus speed. You'll have to know the motherboard, or at least the chipset used on the motherboard. From there you can probably look up the specs and get the speed. It's also possible to use software diagnostic software to determine it. Or maybe even you could find out in the BIOS setup.
50
The Intel 915 GAV motherboard supports DDR SDRAM with a maximum capacity of 4GB. Supported RAM Speed: PC2700, PC3200 (DDR - 400 and 333 MHz) http://support.intel.com/support/motherboards/desktop/d915gav/sb/CS-012066.htm
The ASUS P6T - motherboard is not as fast as the Intel DP39,but it is a reliable motherboard.
Depending on what your motherboard can handle, all the RAM (regardless of clockspeed) will clock to the same speed.