A7V600 vs A7N8X-X vs A7N8X

I'm planning on getting a new rig, and I'm trying to decide between these boards. I might be only using one piece 256 Mb only, so I can't run the RAM in dual channel. Which one would better?

Also, how much of a difference will there be between 256 Mb in single channel mode and 512 Mb in dual channel mode?

Not much (sync or 100%) . The band width will exceed the amount the CPU can use effectivly. On the amount is where you will see a jump in performance from just 256megs to 512megs in both dual or single. 256megs would barely allow XP any breathing room. Are you overclocking at all? If so a single stick runs higher than a dual set up. Memory timings have alot to do with it also. Just depends on what mods your using also... HMM
Seems either boards can do well if you find the tweaks when overclocking that is. As far as stock NF2ultra chipset boards rule.

I'll either get another XP 2500 and push the FSB to 200 Mhz, which is within specs. Or I might get a XP 2400. I'm not going for crazy overclocks, about 2200 Mhz for the Barton or 2300 Mhz for the Thoroughbred at default voltage.

Do any of those boards have a PCI lock?

A7N8Xs do have locks. 2200Mhz is alot for a cpu running 1833 thats alot of overclock and a T-bred at 1533 is one hell of an overclock at 2200MHz LOL

The funny thing is its been so long sense 2200MHz was attainable that its become the norm. I have been running mine for almost a year at over 2300+Mhz stable as a rock. 1800+DLT3C JIUHB 0307 (215x11 UBER1004) RAID as well. Once you get the bug you won't want to stop.

DEF LAN Party revB seems to be really cool . XP will continue to scale (nice 3400+ 3600+ 3800+) next year

I don't want to bother asking the vendor for steppings because they mostly sell retail CPUs now. XP 2400 is pretty close to 90% of being able to run 2300 Mhz isn't it? Right now, the slowest XP that local vendors sell are 2200, but I don't want to take any chances just to save $10.

I won't be needing RAID so would my best choice be A7N8X? Should I get rev 2 or would earlier revs work just as well for 200 Mhz FSB?

Stay with REV.2.0 it is best to stay away from anything lower as FSB is a hit or miss ordeal with earlier revisions. As far as cpu's not to sure about a 2400+? Usually you want low vcore to keep the temp down for more headroom to overclock and i don't think avoiding the steppings that have proven good is wise. Here's an example a vcore default of 1.5 is excellent and one of 1.65 or higher is getting you more MHZ at default but what if 1.5 gave you the same or more at the same system setting in the BIOS. The cons are less heat for stability and just overall better conditions with less tweaks (vcore stock).

A7N8X 2.0 - nVidia nForce2 Ultra 400 (DCDDR400)
A7N8X - X - nVidia nForce2 400 (SCDDR400)

The primary differences between the two are single channel and dual channel memory. Its a no frills board but seems to run fine at 200fsb - i setup a rig for a friend with xp2100tbredb and ran and booted fine at 200fsb (i didn't have time to test it and set it back to stock for my buddy).

Both of these boards come with AGP/PCI locks... And note that teh A7N8X is built on rev. 2.0 PCB boards and will say v2.0 on it.

i got both of the a7n8x-x and the a7n8x i had less probs and better results overclocking on the cheapo a7n8x-x thats what i lefyt in my main rig plus the fact that my slk900u fits on this board ok on the a7n8x bits needed to be bent outa the way to get a good fit
the diference is like 4 mm but it makes a dif at a tight squeeze

Cost difference between the a7n8x-x and a7n8x is $15. Is the only difference between them is that one can do dual channel DDR400 and other is single channel?

I'm running the a7n8x-x board with 2 sticks of pc3200 mushkin black. let me tell you. i was freakin shocked at the performance i gained on this set up. my tbird 1700+ cant handle much more over clocking now, so im upgrading that soon as well. Previously, i ran this:
1700+ @ 2.1 (175x12) vc 1.7v
29C average load
512mb pc2700 micron
a7v333-x

now:
1700+ @ 2.3 (200x11.5) vc 1.65
pc3200 muskin black lvl 2
a7n8x-x

as you can see, this thing gave me so much more room to play with on the fsb.
even without the 'dual channel' this this is awesome.
and what i've been told, the gain for an AMD on dual channel is only about 7%. and for a broke college kid like me, 7% != $15. lol. okay, im done ranting about how cool the -X boards are. especially if you dont need tihngs like RAID or SATA.