I'm looking for building a business/gaming system.  I'm quite interested in the X2 processors, but don't quite understand what they are and what they do exactly that's differene from normal.  I know the FX is lightning fast, but what about the X2 speeds?  Is there any major benefit to it yet, or is the rest of the technology not quite there yet?

The X2 is good if you want to have the ability to have multitask and not eat CPU time of a single Proc. for example on the Athalon 64 x2 4400 you have two cores that have a clock speed of 2.2Ghz and 1MB L2 Cache on each. In a sense you will have the Computing power of two seperate Proc's in the space of a single Proc.
 
The FX series of Athalon 64's is just a single core and is good if you are just building a solid gaming system. They are much more expensive and speed wise they are only at 2.8Ghz max.
 
The main benefit to having an X2 is in the ability to have one core dedicated to doing one task while the other core can handle the smaller tasks that may be asked of it.
 
For what you want to do I highly suggest that you go with an X2 in particular the 4400

So why are the FX processors so much more expensive?  I'm looking at my recent Global Computer cat. and It lists an X2 4800+ as the highest at 859 and the FX 57 at 1049.  
 
What about overclocking?  Can you then overclock one core and not the other on an X2?

The main reason that the FX series procs are so expensive is due to the fact that the over all need for them is not that high. As you said yourself the FX 57 is over $1k and you are only getting 2.8Ghz for speed.  the 4400 which I recommend is only setting at $497 at New Egg.  The FX series Proc's are IMHO the best for a pure gaming system.  
 
The X2's I would think you would be able to overclock one core while keeping the original speed of the other. Though I would have to wonder why anyone would want to do that in the first place. I mean most proc's now are so fast that overclocking would be a waste of time. That is my two cents on that.
 
To be honest since you said you want to build a business/gaming system the X2 is going to be the best bet.
 
Believe me when I say that you really don't need the extra speed of an FX Proc. But If you want the power to run say a Desk Top Publisher, Office software and have a Proc intensive Game all running at the same time then go for the X2.
 
As a builder of systems myself and most of mine are similar to what you are wanting to do I would Highly reccomend going with the Dual Core Proc. Also as a bit of extra buffer for either one I would reccomend at least 2Gig of Ram. Any less and you will be hurting.
 
Hope this helps

 
Ummmm.... WyndKnight..... I can't for the life of me figure out why anyone would want to do this.... let alone how one could achieve it... I'm not disagreeing... rather I'm currious about your thinking... and I'm not saying it can't technically be achieved... I've never tried it nor have I ever considered it....
 
Should you "Overclock" CPU 1 and leave CPU 0 alone.... woudn't you expect the following timing issues between the CPU's; Memory sets...  CPU 0 might want to access the buss at one frequency and  CPU 1 wants to access the buss at a different frequency?  
 
Would you care to enlighten me  just so I can get a better picture?  
 
TIA

I was only guessing myself about being able to overclock one core. As I said I would think that you would. I didn't say that you could or even should. And you are right about the timing issues. It could have problems when one tries to access at one speed and the other is accessing at say it's original speed.
 
but this is completely OT, and this is all I am gonna say on that

While it may be technically possible to overclock 1 core and not the other (leaving out the 'why' question entirely and leaving timing to the experts), it is not possible with today's sockets and mobos.
 
Currently we use mobo settings to overclock the CPU.  Since both cores are driven off the same external (mobo) clock signal, both cores go the same speed.
 
Mike.

FX CPUs are the 'extreme edition' of the A64 line.  They're the best tested chips from the best wafers of silicon from the best line (ok, you get the point 8) ).  They also have the multiplier fully unlocked so you can select any multiplier from 1 to 100 (ok, not 100 but you get the point...   ), AMD's nod to the 'enthusiast' market.  Of course, they can, and do, charge for that.
 
X2's have 2 cores (effectively) identical to the A64's single core on each CPU.  They go from 2.0 to 2.4ghz.  (fastest A64 today is 2.4ghz, FX's go up to 2.8).  Dual core makes the system more responsive when you're doing something that normally would have tied up a single core PC (or at least made it run slow because its busy) like applying photoshop filters, rendering a video, etc., a dual core will either do it faster (if the software is made for it) or at least allow you to switch over and do something else (play games, surf web pages) without the lag and slow response you'd get otherwise.  You can even have lots of spyware, trojans & virii loaded on your computer and not notice it...    
 
For games, technology isn't there to take advantage of dual cores yet, so usually a faster clocked single core is faster in games.  But the X2's are already as fast as their single-core counterparts (excepting the FX series of course).
 
Depending on what you do for business (spreadsheets & word processing, software development, video editing/rendering, etc.) a single core may be better, or a dual core.
 
Dual cores are reported to OC pretty well.  Some say as well as single cores, some say not quite... but heck, a 3200+ Venice core can hit 2.7-2.8ghz easily, so if a 3800+ dual core (same starting clock - 2.0ghz) can't make 2.8, but it still gets 2.6...
 
Mike.

I have heard the 939pin Opterons hit 3ghz easy on air.
I am hoping my opty will do 3 easily on water!

Well, a typical useage for me will be having either a game playing along with windows media player... OR, programming using visual studio.net, editing a map for warcraftIII or Dawn of War, while listening to wmp, OR, surfing with a 56k, lol

I would go for a Opteron 146 and OC it. Or a Opteron 165 if you want a dualcore.

if you are not a serious gamer, go with dual core. the future programs and games will be taking more advantage on x2. and x2 is cheaper than fx, faster when you running most of the programs

Dualcore will drop in price next year.

Dont get EITHER, the the http://www.newegg.com/Product/Prod [...] 6813136166 dfi expert board that has EVERYTHING you could need in your home gamer or office machine AND the opteron 146 if ya want single core or 165 for dual core.  Either proc is 1.8ghz with 1MB L2 just like the FX but clocked alot slower.  They overclock to the same speeds as the FX but cost 190s retail for the single core or 350's dual core instead of nearly $1100.  Its not even a compitition.  And yes, they are 939 socket compatible.
 
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If ya do work on them, the dual core route is best and for the future too.  The dfi expert with the 165 opteron will rock on a nice air cooler and be quiet enough to work and rock in games.  Quiet air can get ya 2.6ghz or more per core (fx55 x 2 cores) for no money practically...

if you take a look at benchmarks for singlecores vs dual cores in gaming singlecores win hands down so get one if you wanna game.

But dual core games just fine also, Do you really notice the gaming difference between a FX-57 compared to a dual core x2-4800?
Both will play the highest res at the highest framerates, but one will get faster as more and more software is optimized for multi-threading... then those same two processors, in a year, which one would be better?

Ok, I'm definatly going for the dual core.
What's all this talk about the Opterons or whatever?  a 165?  Is that the same as an X2 then?

Ok, i'm seeing now that it's basically the same thing, just with the different maker?  What is the big differences between actual X2 and the dual core opterons?

The X2 is for the mainstream casual user, the Opterons are for business workstations.
The Opterons are a slightly better form of the X2's, and run slightly less voltage and cooler.
The Opterons overclock slightly better than the X2's.
Incidently, the cost is withing $20 of the same...
 
The chip specs are the same tho, if you have a choice of X2 or Opty, choose the Opty every time.

Awesome!!!  I thought they would be just a cheaper made cheap or something and would be something to stay away from.  But heck, I think I could spend some dough on that!!  What do you guys think of that Mobo suggested for it with the link just above there?  I have a full case with plenty of room.  I'm not really brand specific since i've only bought an Abit board for my socket A so far.