sorry for this, but I'm not gonna talk about overclocking.

I finally solved my sound issues, as well as my temperature problems.

sound issues : as said before, moved GPU2 to PCI-e 5 instead of 4. temp down by 13° on idle. X-Fi in the free PCI-e 1x remaining below GPU1. replaced bios 1.14 with 1.16 (thanks loonym ). removed all creative components + applied drivers cleaner tips from loonym. installed package from MSI website + patch, then installed CD from mobo (just X-Fi extreme audio, no mediasource stuff). no more sound problem, playing great in my headphones.

temp : GPU is already explained. CPU : replaced Noctua NH-T1 thermal paste with Arctic Ceramique : reported by both RealTemp 2.24 and Corecenter : E8500@31°...

just reinstalled XP properly and sound issue still gone... YES !!!

time for some games and bench now : gonna spend the whole night in front of my new computer... finally, the weekend...