Hmm for Full HD gaming i'd look to hit a HD 5830 or better for a gaming rig and this is very doable with a $1k budget and like you i too enjoy mATX/SFFs rigs hehe In fact i do these up more often than anything else these days for peeps Something for consideration?
AM3 will support the new hexacroes. But to be sure you your new motherboard will support it I would get the 890GX because it will support it out of the box.
The 790 might support it with a bios flash, we'll have to find out.
I personally wouldn't get a M-atx case. They usually don't have very good cable management, poor cooling, USB/ audio are at the bottom / Your stuck with a low end motherboard. Not much future upgradability.
The antec 300 is a small, very good cooling, can fit ATX motherboards, has USB/Sata etc on top. and has good cable management. Will allow you to overclock a lot better then a M-atx case too.
Here's a build with an 890GX
*EDIT* By the way batuchka, the PSU you selected isn't the best, the 750TX/Earthwatts 750 is a ton better. also, the ram I selected is the cheapest ram with the best timings. The 785G will not support the new hexacores, 790 might, and 890GX is proven to support the new cores.
If you were to buy a video card the PCI-x1 slot would be blocked. And then you are only left with one PCI slot.
however, it's not a bad board at all. I just hate M-atx boards.
And you said you weren't crossfiring, but if you were to crossfire the PCI-x16 slots are very very close together. You would lose all PCI slots, and the video cards would probably get pretty hot from being so close to each other.
The top card would be sucking the heat from the bottom card right into it's cooler which isn't good.
By the way, I doubt the P180 will fit a 5850/5870. The case batuchka suggested will though.
*EDIT* Confirmed, 5870 does not fit in the Mini P180
If you really want to be able to update later down the line I would look at the i7 socket. You can drop in a 32nm 6 core processor when they release the non extreme versions. It may cost a little more but imo it is worth it especially if you live near a microcenter. The i7 920 is only $200 and the 930 is $230. You can sometimes find a x58 board there on sale for $140-150 also.
Even if you do not live near a microcenter you can buy used ones on such places as overclock.net. You can find used ones for ~$185-~230 depending on how well that particular processor overclocks.
In one month hopefully the Nvidia gtx 470, 480 will be out to drive down the prices a little bit of the 5800 series cards.
In your title you say sub 1k build, but in your original post you say your max budget is $1400-1500?
I was originally thinking of going with the amd 955/965, but had a question.
will am3 be around for a while?
edit* that 5870 looks good though!
Yep sub $1k , mATX like u want and a ferocious little monster Actually i kindda like the mini p180 too- Egg's out so if you can get it elsewhere that would work for ya as well Also since u stated no CF and if April 26th ain't too far away - 880G/mATX incoming at price points even lower than 890GXes hehe