Hmm so i upgraded my system  from 3500+ + dead 6800gs to  9600 and 5000+ black edition. ( why does it run at 2.8 ghz at stock ?   )
 
 
And im getting pretty low 3d mark score.. as far as i know it is low: under 12k in 3dmark 05 ;/ PLus my MSi 9600gt is factory overlocked ( +50 core + 50 mem) 700/1900
and here is another thing: my card has two connectors besides it's pcie slot. when i first installed it i didnt connect the connectors and when i booted windows said that my gpu is mssing power and made  gpu settings SO that it wont damage. So then i turned my pc off and connected 1 of the wires ( cause i have no slot to connect the other to psu).
Then I booted my pc and no warning showed( even though  only 1 wire is connected).  
So could there be that my gpu lacks some power ? Or did nvidia control panel or whatever. turn some setting down?
I have even set the scroll down to performance!
 
and i am using a 3500+ coller for the 5000+ black edition: it runs at 35-40C is it OK?  

What power supply do you have?

Download GPUZ and see if your card is going full tilt. Dunno bout the 3D marks, how about your games?

I have a Xilence 500w Power supply  it should be ok, or?
mmm and games
Timeshift 1680x1050 4xaa almsot everything maxed out runs smooth.
Stalker: the fps at 1400x900 2xaa everything maxed is high. but game lags. i mean.. yeah really lags. when i go to new area or turn around and see something new.. theres some 2-3 second lagg that really pisses me off?
Can that be caused by my slow 2gb ( pc-533) memory?

And what did u mean by " FULL tilt" john? Gpu-z says its running 700/1900 Oo

If it was underpowered it would go into an underclocked mode

So you have the 6 pin Power connector plugged into the card? I just want to clerify what you mean by 1 wire.

firstly.....cpu temp is more than fine. my 5600+ runs at 32C at ideal and 47C at load.and i live in hot climate. but i suggest u download cpuz n check the speed. 5000+ cant posibly run at 2.8GHz.
secondly, i hav a xfx 9600GT XT oced to 680/1900 and it only has 1 pcie connector.and it works fine even wen i OC it to 710/2000.so urs should b fine.
thridly......performance gain from DDR2 400 to DDR2 800 is hardly 7%.i don thing ram bus is important.
i think sumthing is rong wit ur mobo.or else y wud it show 5000+ runin at 2.8 on stock.....
 
i get 50fps in cod4 1440x900 4x and all setting maxed.
40fps in timeshift at 1400x900 and max settings.
20fps in crysis at 1200x800 with very high settings(shader detail is set to high)
140fps on assasins creed at 1440x900 all setting max wit vsync off.
check wit ur system.
 
also check wit GPZ if card is runing at ful power. when i first installed the card i found my core, memory and shaders running at half the but everything turned out fine after a clean installation of windows. speed.however i hardly noticed and difference in performance between now n then.

Semms like it is really something with my mobo. My poc is not booting now.  
To check whtf is with my cpu at 2.,8 ghz happening i have set the multiplier to 16 or something - save and quit. after that monitor shows "no signal"
mobo isnt even beeping.. lol I am like OMG wtf now IS my mobo down?

You cant just set the multi to whatever.... Go back into your bios and reset it to default and start over

Emm i heard thagt its possible to overclock 5000+be to 3.2 ghzx without changing voltagee sOO  ld i guess i wnt rite L*(
Umm  if i could go to bios i would be the happiest man ever i think. It's just black screen. Nothing is loading, o well i am gonna throw my system out of the window ;/

 
At stock settings like OP said no, but the +5000 BE typically can OC to 3~3.2Ghz fairly easy.

First off, load the defaults of the bios. If it doesn't boot, there should be a jumper or dip switch near the battery of the motherboard that you can switch off and on to reset the bios. Also you can remove the battery from the motherboard (the one that looks like they are for watches) for a bit and it will reset your bios as well.
 
After that, you should be able to get back into the bios. Most likely your bios is set up with defaults and that's why your cpu is showing at 2.8GHz. If your bios has load optimal defaults, that should fix your underclocking of the cpu.
 
That would be the easiest way I can think of.
 
Either that or find out what the settings are for the CPU and input them on the bios.
 
Good luck!

Thanks a lot beeejay82 ! Hell yeah it worked  but my cpu is still 2800 mhz Oo. both bios and windows and cou-z show that