Question My RAM is Unstable

[yullbarez]

Hi, i had two 2GB DDR2 800 MHz Kingston CL 6 RAM and had 6-6-6-18 timings. I've set timing 5-5-5-18 and played CS:GO for 30 minutes system frozen. I've tried to set it stock timing (6-6-6-18) but can't get display and i've reset the CMOS. Now I've set 5-5-5-15. But i can't understand why i can't get display when i set it's stock voltages. I don't have different RAM Kit on my PC. Please help i can't use my PC anymore. RAM running at stock speed.

Specs:
Intel Xeon X5450 3.60 GHz OC (Stable after 5 hours Prime95)
Asus ROG Commando P965 Mobo
Kingston 4GB (2GBX2) DDR2 800 MHz CL6 6-6-6-18
Asus SilentMagic HD 3650 512 MB DDR2 128-Bit
Samsung HD155UI 1.5 TB 5400 RPM HDD1 (OS)
Samsung HD250HJ 250 GB 7200 RPM HDD2
Windows 10 Pro 64-Bit 1909 OS
SilverStone 700W 80+ Bronze PSU

Thanks.

 

[Zizo007]

Why set it to 5-5-5-15? There is 0 difference,