Issues when overclocking a 920 i7; Thoughts on upgrades?

[MagicPants]

So I have an old (c stepping) i7 920 that I've been messing around with overclocking. My motherboard is an ASUS P6TD deluxe.

Anyway the problem I have is that if I go above 3.0 ghz with too many things plugged into the usb ports it won't post. However, I can go all the way up to 3.4 if I unplug a few things, and then plug them back in after it boots.

The USB device in question is the PC xbox360 controller, though I've seen this same issue with other devices.

I'm not really tweaking up the core voltage or anything like that (though I could), and I don't want a massive overclock, just something reasonable. Anyone seen or solved issues like this?

Anyone know if the usb controller on the i7 chip?

I'm planning on doing a major upgrade once lga 2011 comes out. Is there anything minor I could do now? Would a 960 be any improvement?

Here are the system specs:

Core i7 920
ASUS Pt6D deluxe
6 x 2 gigs of 1600 ram (9,9,9,24)
2 x Geforce 580 GTX in sli (to run on a 30 inch monitor)
Enermax revolution 1050 watt psu
Noctua NH-U12P SE2 120mm CPU cooler
Silverstone ft01 case

 

[tlg]

I have quite a few usb devices always plugged and i dont have this problem on i7 930 overclocked.
Maybe it has to do with you motherboard's capacity when overclocking?

 

[MagicPants]

Yeah maybe, just if I new that the usb controllers where on the cpu it wold make a lot of sense.

Doesn't look like there's many gaming benchmarks were a 960 has a huge advantage over a 920 anyway, and I'm already getting 3.0 ghz out of it, so I'll probably just wait and spend more money on an LGA 2011 upgrade.