Hi jake, unfortunately I have tried everything you suggested here to no avail..

I have tested RAM voltage right up to 1.68v and QPI all the way from 1.175v to 1.5v, tried the uncore multi to exactly double my RAM multi, tried having it at 17x and 18x, and nothing works...

I have ran memtest also, and it ran for 20 passes without any trouble as well...

Also, I never use the Turbo and Extreme performance modes, I always have that set to Standard...

Maybe it has something to do with my processor.. as it is still only seeing 4GB of RAM instead of 6GB...

I had suspected it was my original UD5's DIMM slot that was dead, but it does the exact same thing on my new UD5 as well, so I am assuming the IMC on my processor is bad, and this could be what is not allowing me to run my RAM at full speed when I have the processor overclocked...

It runs perfectly at 1600MHz with XMP enabled and manually setting timings and voltages for the RAM with everything else at default settings in the BIOS...

I am getting another i920 on Wednesday next week for my fiancees rig, so I will be able to test out my hardware with another CPU as it is the only thing that hasn't changed throughout all the different hardware configurations I have tested so far, so I am failry confident I have a bad CPU...

But if anyone else can suggest something else that I can try to get my system stable @ 4GHz and RAM @ 1600MHz I am willing to try anything...

Also, I have noticed something strange in the RAM timings page in my BIOS, my Round Trip Latencies are messed up, for the stick of RAM that is in the first white slot the RTL for that stick is usually 60, then the stick in the 2nd white slot is 57, and the last stick is 59..

I thought that the stick in the first white slot was supposed to have the lowest number??

I have tried punching in these settings manually but it doesn't make any difference.. I also noticed that sometimes if I put in wrong values for RTL that my system sometimes only boots with 2GB of RAM instead of 6GB!!!

I remember someone posting on this thread explaining how the RTL was supposed to be, but I can't seem to find that post anymore... could someone else explain this settings for me??

Could it be something to do with RTL that my system is only seeing 4GB instead of 6??

I have tried setting RTL to 60 on the first stick, 62 on the second and 64 on the last one, but it still only boots with 4GB...

Also, even though I have my rig stable with LinX and Prime95 (20 passes on LinX using all available RAM, and leaving Prime95 Blend Test running overnight for around 8 hours) my system will still hang from time to time when playing games like Prototype, or Street Fighter 4... so I wouldn't really class this as being stable!!!

I hope to god when I get this new processor that it fixes all these issues, if it doesn't then I am going to send off my processor, ram and mobo to Gigabyte and have them find out what is causing the problems, as I have spent over a month now testing this system constantly with different OS'es, and as many different hardware configurations as I possibly can with the hardware I have at hand, and I am still not 100% sure what the cause of the problem could be...

Somebody suggested to me that it could be Service Pack 2 for Vista that is causing my problems, could this really be the case??

Though that doesn't explain why I was experiencing these same issues under XP SP3...

If anyone else can give me any suggestions it would be much appreciated...