cpu - Motherboard Specifications Clarification

So, my father (being not so computer-savvy) accidentally bought the wrong CPU for my brothers computer. He was going to send it back, but then I thought maybe it would work in my computer, and my brother could use my CPU. However, I will only feel safe if I guarantee this will work. Hardware specifications can sometimes be just as they are described--specific--but sometimes I've found there are work arounds.

The CPU my dad bought is, as it says on the box, an "AMD Unlocked FX x4" and my dad says its a 3.6ghz clock speed. My brothers motherboard only supports the AMD Phenom II chipset. My CPU is an AMD Phenom II x6 2.8ghz. Here's the first place I'm worried. On the motherboard box of my brothers computer, it says "AMD Phenom II x4". Does this mean that 4 cores is the MAX? If so, then my CPU would not work.

Now, there is also a problem with my motherboard. I have a Gigabyte M68MT-S2P. On the specifications page it says it supports, quote, "AM3 processors: AMD Phenom™ II processor/ AMD Athlon™ II processor". It does not mention anything about this mystical "AMD Unlocked FX (Of which, by the way, I've never even heard of)". Will the accidentally purchased CPU work on my motherboard?

And finally, if all this turns out to work correctly, I have one last question. What would be better, an AMD Phenom II x6 2.8ghz CPU, or an AMD Unlocked FX x4 3.6ghz CPU? I don't want to trade good for worse!

Thanks for helping me out, hardware isn't really my field :)

I introduce you to the AMD FX Processor. Let's put it this way. There's the AMD Athlon processors, AMD Phenom Processors... and AMD FX Processors. You know... Intel makes the Pentium, and the Celeron, and the Core series. Well, this is the same thing, in that the FX is a series of processors.

One of the main features of this new generation of AMD processors, is that they (like the Intel Core series) include an integrated video chipset... right in the processor. Your motherboard supports Socket AM3 processors. It does not support this new generation of processors. So no. This accidentally purchased processor will not work with your motherboard.

Your father will most likely have to purchase a motherboard that will support this processor, in order for anyone in your house to be able to use it. You did not say anything about the motherboard in your brother's computer, so I do not know for sure.

EDIT: Your processor can turbo to 3.3ghz. All 6 cores. This new processor, the AMD FX-4100 that your father bought, does run at 3.6ghz, with a max turbo of 3.8ghz... except that it shuts down all the other cores in turbo mode, and only overclocks two of the cores. So, it all depends on what you are going to do with the computer that the processor is in. In general, your 6 core processor in turbo will be better for multi-tasking as well as tasks like encoding movies and such. This new FX processor will prove better for some games in turbo mode, since most games do not fully utilize multi-core processors.

Checking with the list of AMD Phenoms on Wikipedia makes me guess that you have a Phenom II X6 1055T and the list of AMD FX Processors makes me think your dad bought an FX-4100 cpu.

The FX series uses the AM3+ socket which is optically the same socket as the AM3 but has a slightly different function. It should be downward compatible (you can use AM3 processor in an AM3+ board) but

Note that use of AM3+ CPUs in AM3 boards is not officially supported by AMD.

I would not risk trying this, if you fry anything doing this your warranty is gone.