Voltage and Fan Warnings. Please Help!

Hello

Been having problems recently with heat on a 2nd-hand PC I bought (see sig for specs). However I reseated the gpu and managed to get that temp down quite a bit. I am awaiting an Antec spotcool fan for my northbridge (gets to 60c at load even higher on Prime95) as I dont want to re-apply thermal paste to that as I dont have a clue what I am doing and would mean taking off cpu cooler etc which im really happy with (cpu temps v good).

Anyway...I was having probs with PC Probe II with constant voltage warnings, so on advice I changed all voltage settings in bios from auto to their lowest setting (my pc is stock and not over-clocked). This seemed to have done the trick...however I have been playing The Witcher tonight and noticed my temps were a bit higher than usual and was getting a lot of Chassis Fan and PWR Fan warnings coming up as well as some voltage warnings.

I went into bios and all voltage settings were on green except CPU PLL which kept flashing to red intermittently (approx 1.48) then back to green (1.50). I also noticed alot of my fans values were in red too except these were constant and not flashing back to green.

So basically any help or info is muchly appreciated. Please give any advice in simple lay terms as I am a real novice, thank you.

How concerned should I be over these red fan warnings and voltage (spikes)? I have also had DRAM voltage and SB2 Voltage warnings by the way.

Thanks alot in advance guys!

P.S I have never had my system crash yet...i'm in two minds to just shut off all the monitors and just get on with the damned thing! LOL!!!
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PC Running on 40'' Samsung LE40A656A

PC: Q9550, 4GB Corsair DDR, GeForce 9800 GX2, Corsair 750TX, Asus Rampage Formula MoBo. Cooler Master Cosmos 1000 case. X-Fi Xtreme Sound Card.