I've had my Core i7 920 for about a year now and for almost all of its life with me its been at 4Ghz, its even reached 4.6Ghz, When I first got the processor it managed 4Ghz with a respectable Vcore of 1.26V, since then about every 2-3 months I've had to bump up the Vcore to keep stability, recently the Vcore has been 1.317V for 4Ghz so its getting to the point were I would be considering lowering the Mhz rather than increasing the Vcore even more.
I decided to run 3DMark11 with my CPU @ its "normal" 4Ghz and as I expected it passed fine, but I had forgotten to print screen the results, so I decided to do it again, this time however I got a BSOD during the first test.
The next day I decided to run OCCT to check the stability of the CPU's overclock, low and behold at 4Ghz and 1.317V it was unstable after about 25 minutes. I then upped the Vcore to 1.32500V and tried again, however the CPU was still unstable. I then decided that 1.32500V is as much voltage as I'm willing to put through the CPU for 24/7 use, so the next step was to lower the Mhz and test for stablility.
Now 7 Hours of OCCT is IMO reaching or at stablility considering my PC would never be doing anything anywhere near as strenuous as OCCT for anywhere near 7 hours. So I was happy to call it stable, Howver the next day I was getting BSOD when playing Metro 2033 and a few within 10 minutes of booting into Windows, which I can't understand why.
After all of that I'd had enough and just set my RAM to its default values and set my CPU back to stock.
Today I was ready to give it another go and tried the 3.6Ghz @ 1.32500V overclock, this always BSOD's on me, either before Windows loads or when I apply even a small amount of load on the CPU. Remember this overclock passed 7 Hours of OCCT before.
I then Tried 3.4Ghz with the same Voltage but this gave the exact same results...
I'm completely confussed, How can It of been stable enough for me to use for months @4Ghz with 1.317V but now I can't enough get into windows @3.4Ghz with 1.32500V?
Here's some of my settings for the BIOS I know without checking for 3.4Ghz - 4Ghz
Multiplier x 20
Intel Turbo Boost: Disabled
BLCK 170 (3.4Ghz) - 200 (4Ghz)
Memory Performance mode: Standard
Memory speed (Mhz): Roughly 1000Mhz (3.4Ghz) 1200Mhz (4.0Ghz)
Memory Latency Timings: 8-8-8-24 1T
Memory Voltage: Tried 1.60V-1.66V (Memory is rated at 8-8-8 1333Mhz 1.60V)
Vcore: 1.317V - 1.32500V
IOH Core: 1.200V
Load Line Calibration: Enabled
Most of the others are on AUTO
Temps at 4Ghz and 1.32500V were 57,57,57,54C
System Specs are:
Core i7 920
OCZ 3 x 1GB 1333Mhz 8-8-8-24 1.60V
2 x HD5850's Stock
Corsair Obsidian 800D
CPU and GPU's are watercooled Via Custom loop
Samsung Spinpoint F3 500GB
Lamptron FC6 Fan Controller
So any ideas as to why my CPU no longer wants to play ball? Oh BTW sorry about the really long post...
Are you reporting the same voltage in windows as you did a year ago with the same value? Could be a motherboard voltage drop issue, or your psu.
Another possibility is the mobo just needs to be reset(you know clear cmos), I've seen that a hundred times where a good overclock just start acting funny or unstable. In quite a few cases just clearing the cmos and reinstating the OC settings did the trick.
Lastly it could be electronic migration on the chip it's self, however at the voltage your saying you used it's unlikely this early in it's life.
Yeah I'm not getting the BIOS value for Vcore mixed with Windows Vcore value, A year ago it was 1.26V in the BIOS and roughly 1.24V in windows idle, Recently it was 1.32500V in BIOS and 1.296V idle, Obviously now I can't even get into windows at 3.4Ghz.
I was thinking before that it could be a PSU issue when it failed in 3DMark11 and in Metro as my PC would be pulling alot of power in those situations, however I've been getting BSODs before entering Windows which I assume doesn't use much power.
I'll run OCCT with my CPU at stock whilst running MSI Kombuster Multi GPU with my cards at stock, and if I get a BSOD its likely to be the PSU right?
That looks like normal vdrop to me, so your motherboard is probably fine. Not sure but I believe Everest has a free version that you can check voltages with. HW Monitor is garbage, it just told me my 12v rail was under 11v, my system wouldn't be running at what that program reported.
If all your voltages check out it might be time to make sure all your ram is still good.
Just tried 10 minutes of OCCT+ MSI Kombuster everything at stock and it was fine as you would expect, Gonna download Everest and check the voltages. Your right about HW monitor, says my +12V under load is 1.34V and idle is 0.94V
Ok so I reset the CMOS and went back into the BIOS to find that the CPU was at 133 x 15 = 2000Mhz which I thought was odd for a 2.66Ghz CPU, Anyway I loaded up my 3.4Ghz Overclock and its got into windows and I've played alittle Metro 2033, Gonna do some OCCT testing now. Any idea why that worked?
Some times and it makes no sense at all, motherboards just get sick of what they are running and need to be cleared, even after stability checks. I've been there before, and have witnessed very similar problems, after going through the normal trouble shooting, found that just clearing it and reinstating the OC settings worked. short of that I really can't tell you why.