^^ make a trip to the asus service center first and take the invoice with you.
The mobo I've recommend to you is the cheapest available and is based on AMD 740G chipset. It supports your cpu very well ( and some newer cpus as well ) - no need to worry too much.
^^ get this then Gigabyte GA-MA74GM-S2 - should be around ~2.5k.
^^ remove the rams and try different slots ( if the mobo has any ) or else remount the ram mdule on the same slot properly - if this boots test the mem modules with memtest app.
the fan is NOT running properly. Cleaned the dust but still the same issue. Should I buy a new fan? If so which one and where for my Nvidia 8600 GT?
Removed the graphics card and then tried. Its working fine. The card was quite hot and when examined, the fan is NOT running properly. Cleaned the dust but still the same issue. Should I buy a new fan? If so which one and where for my Nvidia 8600 GT?
You will have to buy GPU cooling fans.
With each rev there are some new fix/improvement/big fix done with the mobo pcb/layout/components.
I can' t tell for sure which rev you'll find in the market but it's better to get the latest one possible .
Can you please share me the link for GT 8600 GPU fans? Am unaware of the same...
^^ can't say how you can find rev number on BioStar mobos - but most probably it's written on some part of mobo PCB - if you look carefully you will find it or else some mobo manufacturers just write it on the box pack - take a look at the mobo manufacturesr website to be sure where this rev no. is written.
Biostar is a good brand - but before buying a mobo if you have any doubts just tell us what model you are going to get or search the web for feedback or review on th particular model.
You will have to buy GPU cooling fans.
^^ get mobos with DDR2 support only ( you have Athlon 6000+ cpu and DDR2 meme if I remember it right ) - it would be great if you can give us the model name/no of the mobos currently available or you are considering to get.
For PSU get Corsair CX430v2 @ 2.2k.