confused on what memory to buy

what is diffrence ecc versus non ecc and unbuffered versus buffered, also if i update my bios will this allow me to use a different type of memory. currently this computer has pc100 sdram, but i have some pc133 sdram and it wont work in the computer that has the pc100 at present, thanks

 

Most desktops use non-ECC, non registered, non buffered RAM. ECC stands for 'Error Correcting Code' and is mainly used in server set-ups. ECC will slow a normal system down because it checks for the accuracy of data coming in and out, and that takes time to do. That function is not needed on a normal desktop, though you can use ECC.
Flashing your BIOS will not permit you to use a faster RAM. RAM speed is mostly dependent on whatever your chipset bus speed is. Example, I'm running a Nivida2 chipset with a 400 FSB, therefore I use a PC-3200 RAM (400 FSB) and the fact that my CPU, an AMD 3200+ (Barton) runs at 400 also sure doesn't hurt either!!
Obviously, your system is an older model so instead of trying to increase the speed of your RAM try increasing the amount of your RAM, IF your motherboard will support more RAM. Since you posted no specs I have no idea how much RAM you have installed, nor the motherboard you're using. If you could post some of your system specs, we just may be able to determine how much RAM your MB can support and take it from there. Or, another option, go to the computer makers website and pull up your system there and see what you can find out.

 

that answered my question, it is an older computer, i am fixing them up for two kids 12 and 14, at the present it has one stick of 64 and one stick of 32, it will support 256. i am increasing it to 256 which is the max. but i did not know what kind of memory to buy, its an Hp XE783, Intel Celeron 700 processor socket 370. motherboard is ASUS CUW-AM/MEW-AM 1.13 i think made by Phoenix. i went to the hp site and it said i could use pc133 sdram, i have that, but it would not work, now what kind it is i dont know, its brand new and come from another computer that is broke, i know its 133. i have several other pc100 sdram sticks that work in other computers but wont work in this one, so i assumed i was mixing it, ecc with a non ecc, reg with a non reg, so i will go buy unregestered and unbuffered, then i bet that will fit. thanks a lot, and sounds like your computer is awesome.

 

What ever brand you decide to buy, just make sure the pin count is correct. I found this on Newegg that may help you
http://www.newegg.com/Product/Product.asp?Item=N82E16820145131
As for my machine being awesome, well since the advent of the 'dual-core processors,' DDR3 RAM, Nivida4 chipsets and a host of other 'speedy' components, my machine is probably considered middle-of-the road, or somewhat below that. Still, the old 'puter does what I need it too do and does it fairly quickly, so I'm happy with it.....for now!! I'm only running 768megs of PC-3200 right now, but I plan to increase that to about 2 gigs within the next month or so and that'll probably take me through another year.
Well, good luck and if need anymore help come on back.