I've currently got a store-bought Compaq computer with an MS-7184 Socket 939 motherboard and a Sempron 3400+ CPU inside. I'm going to upgrade it soon, but I'm having trouble deciding which way to go.
Should I simply grab another socket 939 chip, like an AMD X2 4800+? It'd be an easy upgrade, but from what I've been reading and looking at it's hideously expensive for the performance I'd be getting.
The other thing I've been looking at are Intel C2Ds and their regular dual cores, the E2160 in particular. From what I've read and heard, the E2160 is basically a C2D with less cache and a ton of overclockability. Going this route requires that I buy a new mobo, which brings me to my first question: How can you tell whether or not a motherboard will fit in your OEM case without having to rip it apart and taking precise measurements?
Since I'm considering overclocking the E2160 via the bus speed, which will also increase RAM speed, my next questions this: If I overclocked the bus speed from 200 to 333, and thereby make the RAM go from DDR2-400 to DDR2-667, what speed RAM should I buy in the first place? Do I buy DDR2-400 and let it overclock, or buy DDR2-667 to be safe? Does it even matter?
The last thing I'm wondering about concerns the power supply. I'm running off the OEM Bestec 220-250w PSU at the moment, and that's obviously not going to handle an overclocked CPU and a possible 8800GT in the future. From what I've been reading, 8800GTs need about 25A of power on the 12v rails. The question I have is this: For PSUs with multiple 12v rails, do you count all the amps available, or does a video card need all 25 amps on one specific 12v rail?
The last questions I have are also about the power supply. I'm looking for a relatively efficient unit, and I was trying to figure out how the efficiency rating factored into the amount of power actually supplied to the computer. Say I have a 300w PSU with 80% efficiency at all loads. Does this mean that the PSU only gives a minimum of 240w (80% * 300), or does it mean that it constantly gives 300w but draws power from the wall socket at 80% efficiency? Also, what PSU brands are good? I've been getting warnings that PSUs should not be skimped on for the sake of price, but the only brand I've really heard anything great about is Antec. Any recommendations?
Note: price is definitely a consideration for me, although I'm not gonna buy the cheap generic stuff on critical components.