Pass Intel Burn but Prime95 crashes

nickeverett · 19 Apr 2012 at 10:45

I'm new to overclocking, so I've been reading a lot of guides and then started to experiment myself.

I started at 4.5ghz 1.3v (1.28v - actual after vdroop) which was stable after intel burn x10 on max and Prime95 for an hour.
Then 4.6ghz 1.3v (1.28v) - stable after IB and Prime95 for 1 hr.
Then 4.7ghz 1.3v (1.27v) - BSOD 101 on intel burn after 5 mins

Now 4.7ghz 1.31v (1.29) - passed intel burn x10 max. Prime 95 (Blend) crashes after 10 mins.

Images are clickable for full res.

IB passed

Prime95 crash

Does the prime95 crash mean the overclock is unstable or is it OS related? Would a fresh windows install help?

Or should I just keep raising the vCore until stable on IB and Prime95?

nickeverett · 19 Apr 2012 at 11:06

BIOS:

Ai Overclock Tuner: XMP
Turbo Ratio: 47 per core
BCLK: 100.0
PLL Overvolt: Disabled
Memory Freq: 1600Mhz
EPU: Disabled
LLC: Ultra High
VRM Freq: Manual - 350
Phase Control: Optimised
CPU Current: 140%
CPU Voltage: Manual 1.31v
Speedstep: Off

Everything else on standard settings

Si105 · 19 Apr 2012 at 11:09

4.7 on 1.31 VCore

?

nickeverett · 19 Apr 2012 at 11:16

Si105 said:
4.7 on 1.31 VCore ?

too low?

There are lots of similar OCs here: 24/7 Stable Sandy Club Spreadsheet

"crazyreefa 4700.6mhz 1.280v 15hrs 59-66-69-63 AIR - 212+ 2500k 8GB 1333mhz
sq_a380 4700.7mhz 1.304v 12hrs 77-83-83-80 AIR - 212+ 2500k 8GB 1600mhz"

Rik1254 · 19 Apr 2012 at 11:20

That looks to me like Prime is crashing. Uninstall, redownload and reinstall.

Also, Ive noticed with Asus board, when you set the voltage to manual, it knocks off Intel Speed Step, so the CPU will constantly run at [email protected], it will never drop....unless they sorted this with the Z68 boards.

nickeverett · 19 Apr 2012 at 11:27

Rik1254 said:
That looks to me like Prime is crashing. Uninstall, redownload and reinstall.

Also, Ive noticed with Asus board, when you set the voltage to manual, it knocks off Intel Speed Step, so the CPU will constantly run at [email protected], it will never drop....unless they sorted this with the Z68 boards.

Thanks, I will re-install Prime95

My CPU drops to x16 when idle. Then straight up to x47 when load. but voltage always stays at 1.31v

I am to set an offset voltage when I've found a stable clock and vCore. I am aiming for 4.8ghz, with vCore under 1.350, but not sure I'll be able to achieve it.

PaulyD · 19 Apr 2012 at 12:27

I got prime stable with a 1.332v load in cpu-z @ 4.6ghz but had to bump up the VTT to do so (had the exact same issue as you nearly. IBT stable for 50 runs of Max mem but would BSOD in prime after few hours).

Try raise your VTT up a few nudges and retry.

4.7ghz seems to need a hell of a bump in voltages for me

happy with 4.6 at these volts though

TwsT · 19 Apr 2012 at 12:40

VTT often labelled VCCIO should not go much over 1.2 believe there is a great Sandybridge overclocking thread on Overclock.net forums that i would recomend you read

But yeah re-install prime first as it should crash a core (go red and stop running) or bsod. You appear to be getting a software crash.

I would expect it to be fine tho ibt uses similar things to linpack benchmarks and they are very cpu stressing much more stressing than prime. Prime simulates more everyday use than a full out cpu thrashing.

Jokester · 19 Apr 2012 at 12:46

Prime will often blue screen if your PC isn't stable.

Cold_And_Miserable · 19 Apr 2012 at 21:27

Jokester said:
Prime will often blue screen if your PC isn't stable.

I wouldn't want to ever get that unstable. Windows file corruption would be guaranteed.

I find preset modes: blend and small FTT to be very easy to pass but still get BSODs in games, freezing during video playback etc... Custom mode with maximum RAM usage and 512kb-4096kb has kept things stable for over 2 years.