Can't get stable Xeon X5450 OC

[Raizin]

Hi guys, recently I bought X5450 to my 775 MB Asus P5B Deluxe.
Everything works fine but now I want to overclock this CPU casue it's bottlenecking my R9 270X.
I tried 400FSB on 1.25v without any other changes and that was stable but in games I had micro stutters, so I put voltage to 1.3v and boom everything ok, no bottlenecking no stutters. And that was yesterday, today I turned on my PC, wanted to play some Witcher 3 and what? Stutters.
I don't know what to do now and I ask you for help casue I don't want to broke something

Btw sorry for my english, It's not my 1st language.

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Temps are fine, 34C idle and about 60C load. Revision of this CPU is E0 also my PSU is XFX PRO 550W

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Oh and I forgot, I have @3,6Ghz 400x9

 

[Raizin]

Actuall rig

X5450
4GB RAM 2X2
MSI R9 270X
XFX PRO 550W
Silentium PC Fera 3 v2

 

[trents]

http://en.cdprojektred.com/support/tw3-system-requirements/

First, you don't meet the minium requirements for RAM

Second, your CPU and the whole socket 775/DDR2 platform is inadequate.

You need to at least upgrade your motherboard, CPU and RAM to newer stuff.