Q6600 hiccupping when OC'd

[tre4]

Okay this machine is not new and I've been thinking to go i7 but first I thought I'd over clock see if I could squeeze it up a bit.

I got the thing up to 3ghz fairly easily which left my memory running exactly at stock but then had stuff to do so I thought I'd leave getting the next Ghz out of it till later. I booted it and started using it and from one point of view it run rock solid however it seemed to have gained a slight stutter. operations like moving the mourne seemed to have gained the tinniest delay but added up the experience became frustrating. Any way last night I asked my wife if she'd noticed the PC doing anything strange. she described the same stuttering so I reduced to stock and all was fine.

Memory running at 667 (which is Spd although rating is higher OCZ2N1066SR2GK)

cpu is a GO stepping Q6600 at 333 x 9 (temps 50 ish to 42 ish across the cores)

PCI-e fixed to 100

Motherboard is a Gigabyte P965-D3 (rev 3) from memory.

I have a thermaltake NB cooler with zip locked small fan and an Zalman 9500

I've only just started the easy bit and fallen at The first hurdle, what am I doing Wrong.

 

[tre4]

I was running the memory at 667 by changing the ratio so exactly at the sPD value. I was using default voltage though as I'd not got as far as clocking the ram. Its sold as 1066 does this sound right?

I'm using 4Gb in 1Gb sticks though and I know that I had to drop the timings on the ram from stock when I added the second pair.

I'm only running a 400W Psu I do you think that may contribute? (graphics card is only an 8600 GT so no big drain.)

kinda minded to dump the setup and go for an 860 with 860 with 8Gb of Ram. Current setup is stable but plodding at stock, enough that the Wife notices and would not resist investment!