Core 2 Duo e6750 + 680i lt overclock limiting factor?

I recently rebuilt my computer from a:

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CM Centurion 5 case
E6750 (running at 2.8 Ghz, vcore=1.35)
Intel cooler
680i lt MB (Auto voltage)
4 x 1 GB Crucial Ballistix DDR2
<>Factory: DDR2 1066, 5-5-5-15, 2.2v
<>Stable: DDR2 700, 4-4-4-12, 1.85v

Into:

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Antec 300 case
E6750 (running at 3.1 Ghz, vcore=1.35)
Sunbeam Core Contact Cooler
680i lt MB (Auto voltage)
4 x 1 GB Crucial Ballistix DDR2
<>Stable: DDR2 775, 4-4-4-10, 1.85v

I attempted to further incrementally increase the overclock today without success with the following:

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CPU: (3.2 Ghz, vcore=1.375)
FSB: 400
Ram: DDR2 800, 4-4-4-8, 2.0v

With 3.2 Ghz being my target, due to the 680i lt MB having a max ram speed of 800 Mhz, I would like suggestions on what should try to get to my target. Of note, however, is that I do not want to increase the voltage on any components "too high" due to component burnout. (This especially applies to the FSB, as the 680i lt series is actively cooled, and always runs very warm.)

I am using Prime 95 for stability testing. Further, with the 3.1 Ghz current speed, Speedfan reported a max temp of 55c. (However, it usually ran ~50c.)

Thank you in advance.

My thought as well, but based upon:

http://www.overclock3d.net/reviews [...] b_ddr2_kit

I assumed the ram should be able to handle 4-4-4-8-2T at 800 with 2.0 volts, since the review successfully ran them at 4-4-4-8-2T at 1066 with 2.35 volts. But, as all know, all chips are different...especially the later revision.

Will update with new information tonight once home from work and testing proceeds.

I think you have made the correct call on this one, take care.