I want to rant something here.

My argument is: Are Corsair Value Select DDR2 rams really suck?

Yeah... so much on the "reliable, qualified, tested, compatible" claimed by Corsair. Here I have 3 brand new Corsair Value Select DDR2, and only one of it is working. I have 3 pc in the house (unfortunately all of them are AMD) and none of them boot with these 2 stupid rams. I've checked with all three motherboards website regarding memory compatibility issue and none of them listed CVS. But somehow, one RAM does work without any hiccup...so I take that the compatiblity test wasn't really accurate. Tomorrow I'm gonna go over my friend's place to test on his Intel.

Since I'm talking about DDR2, I have never had any single problem with Kingston Value RAM and Crucial.

My suggestion here: Beware careful of Corsair Value Select...they're expensive for nothing.

did i post here in regards to your query? i think my post kena deleted 

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if ur current 2x1gb adata able to run cl4, then it's definite wise to just add-in another 2x1gb cl4-800.
that'll gives you 4x1gb cl4-800

as for the 4 sticks vs 2 sticks concerns,
the stress on mobo often relates to the difference in max. oc between them.
while you are running @stock ddr800 (1:1) , i see no problem on that.
the heat from additional 2 sticks only concerns when u oc/increase vdimm on it.
in ur case, ddr800 is stock, so no problem on that too.
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if ur current adata only capable of cl5-800,
and you considering between buying another 4sticks on 1gb , or 2x2gb
then 2x2gb is definitely ur choice, as you are not into clocking high speed.

so if you were to going for 2x2gb, just pick the cheapest kit rated cl4-800 as u don't need high performance kit,
as although they prove to clocks quite nice on speed, but don't forget you are running 8x400.
u need no more than ddr800. (though some may argue that they can pushing the ram alone using divider/multip. , but it's generally pointless to do so.)

do note that the difference between cl5-800 vs cl4-800 , is very minimal.
so i'd actually prefer the 1st way which is just add in another 2x1gb to form total of 4gb.
but best if ur current adata able to do cl4-800, then 4x1gb is definitely the way to go.
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as for best results on ur case "without the concern of $$$" ,
as you'r running 8x400, i'd reckon cl3-800 1:1 setup.
there are 2x1gb cl3-800 kits around (eg. kingston hyperX pc2-6400 cl3 2gb kit.)
two sets of them gives u 4x1gb cl3-800 1:1 setup.
(i don't recall any 2x2gb sticks able to do cl3-800 , as 2gb sticks doesn't have l337 chips on them.)
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I have this XFX 780i mobo... I tried putting 4 stick Dorminator but when booting, it says 4 DIMM not supported? My 4 stick Dorminator tested all no problems... I swap slot and swap Dorminator using 2 DIMM slot no problem...

Use 4 DIMM slot... after boot into windows... only 2 gig is recognise... WEIRD!!???

Can anyone guide me any ways to test my ram whether they are faulty or not? I keep randomly getting BSOD, reboot etc and Vista detected a hardware error during Memory Verification.