DRAM Ratio Issues

[Broadwater]

So, I just installed a set of Crucial Ballistix PC2-8500 modules and find that the system becomes unstable beyond a DRAM/FSB ratio of 2.66

The odd part about this is that this memory is rated for 1066MHz and with my FSB at 333 and the ratio at 2.66 the memory is only running at 886MHz; which is fine because it is stable here. At a ratio of 3.0 (1000MHz) the system becomes unstable. The BIOS, CPUZ and Everest all say the memory's max bandwidth is PC2-6400 which is incorrect as these modules are PC2-8500.

 

[Quiksilver]

What vDIMM voltages are you using? Also have you pulled out one of the sticks and read the little sticker just to be sure its rated for DDR2-1066?

 

[Broadwater]

vDIMM is set to "Normal" in the BIOS and the options are to add voltage by +0.1v rather set the actual voltage e.g. 1.8, 1.9, 2.0 etc. These modules are rated at 2.2v and my previous Mushkin modules were rated at 1.8v! As best I can tell the P965 chipset supports up to PC2-6400 so it might not be realize this is anything beyond that and as such may only be supplying 1.8 vDIMMM. If this is so I might need to up the vDIMM by +0.4v
However, if the BIOS is already supplying 2.2v and I add +0.4 I'd end up with 2.6 vDIMM which will most likely fry my RAM. When I do set the memory to run at 1000MHz I have to power on and off multiple times to get it to boot, however once it is in Windows is runs perfectly stable (Everest Stability Test). Most of the time setting the memory to 1000MHz causes the computer to power on and off by itself before a successly POST and sometimes after the successful POST the BIOS will reset itself and I'll end up back at square one.

 

[imported_Scoop]

If the memory is rated at 2.2V, that means it's rate to work at 1066Mhz at 2.2V. I think the default voltage on Gigabyte boards should be 1.8V, but check the manual. You could also try raising the northbridge (MCH) voltage and see if it helps.