I have 4 DDR2 memory slots and I know that 1&2 and 3&4 have to be paired, but do 1&2 VS 3&4 have to be paired?

If not will this effect the performance of my computer? This is because I currently have: -

1&2 = 2x 512mb PC2-4200 533mhz and 3&4 = Empty,

but I want to do this 1&2 = 2x 1gm PC2-6400 800mhz and 3&4 = 2x 512mb 533mhz

:help:

NONE of them HAVE to be paired, Unless you want to use Dual Channel (which is a good idea) -- and if your board configuration is 1+2 and 3+4 as you say, then no... 3+4 DONT have to match 1+2 --- and its pointless getting the 800Mhz ram, as it will only run at the slower 533Mhz speed

my board configuration is 1+3 2+4 -- and, I have 1+2 = 1GB, and 2+4 = 512Mb..

The DDR modules have a lower and upper operating voltage , something along the lines of 1.9V-2.3V, so long as there is a common voltage you can mix them, but it's not wise to do so. Stability may be a problem and they'll only run at the speed of the slower RAM (not just mhz but also timings).

Personally I'd bin/sell the 2x512s and keep the 2x1gbs. Even with Vista it's very unlikely you'll currently use/need more than 2gb of ram (for "normal" computer day-to-day use).

:O Vista eats ~800 mb just on a clean boot.... I have 3GB and Vista uses over 50% regular... anything less than 3GB and I would worry :/

I have 3GB and Vista uses over 50% regular... anything less than 3GB and I would worry

That's largely a myth that was spread around the 'net when Vista was first released, it's been (mostly) debunked since. I say "mostly" because Vista does unquestionably use more memory than XP, but doesn't need as much as you think.

MS changed the way memory is handled by the OS in Vista. RAM is now used as system cache (like an extension of L1 and L2 cache). In effect; Vista is constantly trying to preempt what you will do in the future and transfers anything it thinks you are likely to use from HD to RAM. The idea being that empty ram is wasted ram (after all, it takes significantly longer to pull things from a HD than from memory). Should any of this memory ever be needed then it will be instantly cleared down and remapped as usuable. If Vista isn't using a significant amount of your memory then it's not doing its job properly.

Read up on superfetch:

http://www.tomshardware.co.uk/2007/01/31/windows-vista-superfetch-and-readyboostanalyzed_uk/
http://www.microsoft.com/windows/products/windowsvista/features/details/superfetch.mspx

But then when its got it wrong, and hasnt got what you need in ram, it takes longer to load as it clears X ammount, and loads what you REALLY DO NEED into ram, but then say you need more.. such as with gaming..

this is confirmed as why gaming performance has dropped in Vista, as Games require empty ram also, to swap and switch textures with the GFX, and if vista isnt leaving enough for the game, the games performance is reduced...

But then when its got it wrong, and hasnt got what you need in ram, it takes longer to load as it clears X ammount, and loads what you REALLY DO NEED into ram, but then say you need more.. such as with gaming..

Clearing down memory to be reused takes, quite litteraly, next to no time (we're talking nanoseconds).

this is confirmed as why gaming performance has dropped in Vista

Not really, immature drivers is a far bigger factor (most are only just out of beta, compared to 5/6 years development time on XP). Another large factor is the greater emphasis placed on the graphics card in Vista, it loads aspects of the display onto the GPU that would otherwise (in XP) have been processed by the CPU.

Despite all this, you'll rarely notice any slow down, most games run 5-10% slower, with most DX9 games flying at over 100fps on current hardware the only people who will be bothered by the 5-10% loss are teenagers who think FPS = penis size, you won't be able to visually see any difference. Of course: it's impossible to compare DX10 games as XP wont run them.

I disagree withthe "you wont be able to visually see any difference" when i used vista, on this machine, I diddnt even look at the frame rates 'first thing' I loaded the game, attempted to play, thought "this is running a little sluggish, i wonder what the frame rate is" -- so looked, it was ATLEAST 30% lower than with XP, and thats on any games, its between 15% and 30% lower, you notice such things on games like Natural Selection, Half Life 2, etc...

and I agree with the fact that the drivers are a huge part to play in the fact the gaming performance sucks so much on vista, however older games (Worms 3D, and Forts under Siege for example) dont run at all on vista, and its not like they are 'OLD' games... Vista has poor compatability, doesnt support EAX on anything other than X-Fi Cards (even then a patch is required) -- i think Microsoft need to release the HAL for sound, and fixes for older games in thier SP 1 for vista...

I disagree with the "you wont be able to visually see any difference" when i used vista, on this machine, I diddnt even look at the frame rates 'first thing' I loaded the game, attempted to play, thought "this is running a little sluggish, i wonder what the frame rate is" -- so looked, it was ATLEAST 30% lower than with XP, and thats on any games, its between 15% and 30% lower, you notice such things on games like Natural Selection, Half Life 2, etc...

and I agree with the fact that the drivers are a huge part to play in the fact the gaming performance sucks so much on vista, however older games (Worms 3D, and Forts under Siege for example) dont run at all on vista, and its not like they are 'OLD' games... Vista has poor compatability, doesnt support EAX on anything other than X-Fi Cards (even then a patch is required) -- i think Microsoft need to release the HAL for sound, and fixes for older games in thier SP 1 for vista...
Yes, Vista has too many problems at present. I run XP Pro on an AMD 64 with 2X512MB RAM and striped Raptor HDDs. [Presently an nVidia 7600GTS card.] I'm sticking with it for now!

Out here computer resellers are starting to advertise the option to stick with XP Pro as a feature. Maybe when Vista SP2 comes out?....