Can anyone tell me why this modest overclock is unstable?

[auric]

First, my specs:

Gigabyte x58-ud3r rev 1.6
Intel i7 920 SLBEJ OEM cpu
GTX 260 Gainward Golden Sample gfx card
OCZ gold 3gb 1600 mhz ram (8-8-8-24 timings)

On optimized defaults, my computer seems to have no issues.  However on the overclocks I've attempted I experience one of two things: my computer suddenly powers down (as if I had hit the reset switch) or it locks up, accompanied by screeching noise if I'm inside a game.  It seems to happen about once a day on average, and more often when I'm playing games or playing movies.  It makes me wonder if it's an issue with the PCI-E or gfx card.

The overclock is:

Clocks:

CPU: 3.4 ghz (x17)
QPI: 7.2 (x36)
Uncore: 3400 mhz (x17)
Bclk: 200
PCI-E: 100 mhz
RAM: 1600 mhz (x8)
Timings: 8 8 8 24
Intel turbo boost tech off, EIST on

Volts:

Vcore: 1.0875
CPU PLL: 1.3
QPI: 1.175
IOH core: 1.14
QPI PLL: 1.14
ICH I/O: 1.5
ICH core: 1.1
DRAM: 1.66

[oggmonster]

Where does the screeching noise come from? Is your PSU definatly okay. Not had any expierience overclocking with i7 but you may possible need to bump up CPU and possibly QPI volts.

[auric]

Screeching is on the audio.  It seems to be a typical thing to happen when the computer locks up and sound is playing.

[Alpha]

Hello 

Could you tell us how much power are your PSU ?

By my experience , If the Hardware are under powered , the Overcloking will fail (shutdown , restart loop) .

Me , i am under powered . My PSU are 400watt and i am running a p45 with x2 2giga ddr2 , a Core 2 duo E7200 and a HD3870x2 .
Now , just for the HD 3870x2 it need a 500watt PSU at least , Yet , my Rig work fine and super stable . I even can Softly overclock CPU,GPU to gain a extra punch for some game.
But wen it come to overclock medium or HARD my PC does exactly what your PC do.

If it is not the POWER of your PSU it could be that your PSU (maybe a capacitor with in) cant take the charge and shut -restart your PC .

Try with a other brand PSU and for the most ...stupid ,  check if your RAM are properlly plug into the RAM slot .
Bad RAM do shut-restart the PC too .

i hope it help 

[K404]

Try:

Vcore: 1.12
CPU PLL: 1.3
QPI: 1.225
IOH core: 1.175
QPI PLL: 1.175

Might not be enough but im pretty sure it will be a step in the right direction

Maybe try PCI-E to 105MHz and maybe turn QPI speed down a notch RAM is x16.. QPI should ideally be x32

[ETNiES]

Stick to a 20 multiplier 920 D0's prefer the higher multi unlike older processors, im using 191 x20 Turbo on to give me a 4ghz overclock.
and up your vcore its far to low for an overclock up that

[Badbonji]

Vcore needs to be raised a little I think, 1.08 is quite low!