Overclocking Hitting a brick wall with my i7 920 - (Solved)

I got my new i7 build going this week and while the stock speed is already a pleasantly big jump up from my E6600, stock is never acceptable.

I have the i7 920 sitting prime-stable at 3.8GHz currently, but I seem to have hit a brick wall on my way to 4GHz.
The system seems to be happy and prime-stable with the base clock at 200MHz, but if I switch the multiplier up from 19 to 20 it hangs at the Windows boot screen.
I've kept the memory relatively slow (1200MHz) to take it out of the equation.


Components:
-Core i7 920 (C0 stepping)
-3GB Corsair Dominator 8-8-8-24 1600 DDR3
-Gigabyte EX58-UD5
-8800GTS 512MB
-Corsair HX620 PSU
One WC Loop;
-EK Supreme LT on the CPU, Swiftech MCW60 on the GPU
-Two radiators, 3x120 and 2x120

Current settings:
Base clock: 200
Multiplier: 19x
RAM speed: 1200MHz
DRAM multiplier: 6x
QPI Link speed: 36x

CPU Vcore: 1.425v
QPI/VTT voltage: 1.34v
DRAM Voltage: 1.66v (as close as I could get to the 1.65v rating of the Dominator modules)
All other voltages on 'auto'

CPU features like HT, Turbo and enhanced halt states all disabled

Resultant CPU clock: 3.8GHz

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I've tried bringing the base clock down to 190 with a multi of 20x to replicate that same final clock with a higher multi but the system just locks up after POST.
Similarly, if I leave the multi at 19 and increase the base clock I can't get above 204 without seeing lock-ups.

This seems kinda strange, since I would have expected the base clock to limit me before the multiplier or overall clock.

The 1.425v Vcore is pretty high for 3.8GHz, too. I can probably shave a bit off that and stay stable at 3.8GHz.
I experimentally raised the VCore to 1.525v eeek but the system still locked up, so I don't think it's a vcore issue, unless this CPU is really a juice-guzzler.
Most other people seem to be over 4GHz before needing to go past 1.45v..

-

The CPU stays below 55C fully loaded with 8 threads at 3.8 so I'm pretty certain it's not a heat issue and that I've plenty of headroom left in that regard.

It seems that I'm either missing one voltage that I could change to get the multiplier stably up to 20, or that my CPU is 'a dud', in that it just won't go over 3.8.
CPU PLL? IOH? I'm not certain quite what those voltages relate to, so I'm dubious about pushing them up yet.

I tried enabling the Turbo to see if that would give take me up to 20x under load, but I've never seen it kick in whether one core is loaded or all 4(8 threads).

The system is fast as hell at 3.8GHz, but I'd love to hit that solid 4GHz and get it prime-stable, so I'd appreciate any tips on getting those last 200MHz.

 

Only a free 1.2 GHz overclock, Intel screwed you
Anandtech has a good article about two retail I7 920s, and their respective OC ability.
http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3502
They also test the new D0 stepping I7s, which seem to clock even higher, well at least their one did.
I hope you not planning to embarrass your I7 for too much longer with the 8800 GTS, come on it wants to hang out with the trendy crowd

 

There's a list of binnings available and compiled by one of the overclocking websites (forgot which one) and their maximum overclocks. For the most part 3.8Ghz is considered to be the best binned 920's and therefore you should be happy; that brick wall is something everyone is hitting without liquid nitrogen. Very few people have posted a 4Ghz+ overclock; and they're not stable or practical. The CPU is a power guzzler, and due to the IMC putting more volts through it will just toast your memory controller and brick the CPU.

Edit: Found the list; posted below:

In case you need to know the best batch (it also depends on luck)

============================
Core I7 920 A Batch:

-3836a381
Chri$ch-3800.1Mhz q 1.232V HT On
Chri$ch-4009.3Mhz q 1.360V HT On
Chri$ch-4200.2Mhz q 1.440V HT On
deepsilver-3599.9Mhz q 1.248V HT On

-3841A383
JWMc-3800.0Mhz q 1.218V HT On
16floz470ml-3827.6Mhz q 1.195V HT On
Tot31-3500.0Mhz q 1.056V HT Off

-3839A403
Chicken Patty-4303.5Mhz q 1.435V HT Off

- 3837A507
Nordien-4217Mhz q 1.400V HT Off

- 3836A531
Mascaras-3800.1Mhz q 1.200V HT On
Mascaras-4000.2Mhz q 1.344V HT On
Mascaras-4312.0Mhz q 1.376V HT On
-3838A554
Loc.o-4000.0Mhz q 1.325V HT On

-3838A646
Uberbob10200-3400.0Mhz q 1.153V HT

-3837A728
ShoNuff-3800.1Mhz q 1.2248V HT On

Bobbylite-4200.0Mhz q 1.344V HT Off
- 3835A766
Beast200-4200Mhz q 1.425V HT Off

- 3837A768
Ghigo-3800.0Mhz q 1.34V HT ?

- 3836a772
Gligy-3800.0Mhz q 1.264V HT On

-3836A866
Jupiter-3800.0Mhz q 1.232V HT On

-3836A867
Metroid-3717.8Mhz q 1.160V HT Off
Metroid-4009.2Mhz q 1.248V HT Off
Metroid-4009.0Mhz q 1.272 HT On

- 3837A909
Tjelaw-4200Mhz q 1.362V HT On

------------------------------------

Core I7 920 B Batch:


-3837B072
Webwilli-No Results Posted.
Chri$ch- No Results Posted.

-3838B079
Namegt-3780.0Mhz q 1.168V HT On
Namegt-4000.2Mhz q 1.216V HT Off
Chri$ch-4011.2Mhz q 1.248V HT On

-3837B080
Dj883u2-3705.0Mhz q 1.088V HT On
Dj883u2-4010.0Mhz q 1.152V HT On
Dj883u2-4104.3Mhz q 1.264V HT On
Dj883u2-4515.0Mhz q 1.376V HT On

-3837B215
DerekT-3183.5Mhz q 1.136V HT On

=========================

Personally I have the 3836A866 batch; but I'm not really interested in testing out the limits of the CPU for now... the system is fast enough for me as it is.

 

I know, it's cruel!
Make it a free 1.35GHz overclock now, though.

Yeah, the D0 seem to be better on average from what I've seen, but I'm not going to try and return mine to a retailer on those grounds.

The GTS512 does the job for now, I primarily upgraded to an i7 and DDR3 for the memory bandwidth and quad-core processing, the E6600 I had was fine for gaming in most cases.
I do a lot of audio production and music recording, as well as experimental audio programming, so having this hardware makes that a whole lot easier and more exciting.

I do plan to replace the GTS512 eventually though, when I've got the cash to spare

I'm not so sure about that - Most forums and reviews describe 3.6GHz as 'easy' on the i7, and 3.8 to 4GHz as realtively easy even on air.
Thanks for the batch info though, it's nice to know in case I'm buying another - I'll know what to look for.

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Anyway, I've done it now.

Switched HyperThreading off again, Set the Uncore to 15x, VCore to 1.5v, dropped bclk to 191 and upped the multi to 20.
Then I got turbo working and CPU-Z is reporting 4011MHz (191x21) under load.
I think the uncore and HT were the keys to it, as I had left the uncore at 13x in every other attempt and dismissed HT as irrelevant.
On Gigabyte X58 boards Turbo works outside Intel's specs by increasing the multiplier for all cores instead of just 1 or 2, so it effectively gives a 'free' extra multi on 920s.

I'll post some screens once I verify that it's prime stable overnight, then I'll tweak down that high VCore and retest
20 mins without crashing or any rounding-errors so far, Cores at ~60C.

Update:
========

Got the VCore down to 1.475, still stable. I tried going as low as 1.4V but got BSODs and again at 1.45.
Temps are consistently at ~60C under load, so I think it should be okay at that voltage.



Next up is to get the RAM running higher, but frankly I'm not sure it'd make any difference. If I get bored I'll give it a shot.

Update 2:
=======
System crashed at 1.475 after a while, so I'm back up to 1.5v Vcore now to stay stable.
Makes me wish I had a D0.

 

Got to say the new DO cores are fantastic.

At present I have manged to get my i920 up to 4494 (21x214). I've had to enable LLC and set the Vcore to 1.3875. Quite a bit of Vdroop on my board as CPU-Z only displays 1.36v
The setting that caused me lots of issues was CIA 2. This was enabled in my bios at first. Once i disabled that, the overclocking went far easier. Only got this chip last friday so overclocking i7 has been a new challenge.

Anyway, proof of the overclock:

 

More details if you please; how is cooled, stability,....

Thanks.

 

My motherboard is the Gigabyte X58-Extreme (fantastic board, just wish the chipset blocks came with different connectors for watercooling. Mine came with connectors for 10mm piping. Waste of time for me).

QPI voltage is at 1.36. Apart from the ram all others are on Auto.

I have 3x2gig of corsair dominator PC3-12800. For this benchmark I ran it at 1712mhz (214*8), 1.64v at 8-8-8-24 @ 2T.

It's watercooled using a Swiftech Apogee GTZ.
This is only a benchmark set up. With HT enabled its hitting high 70's when prime 95 is running.
As I only got it to this o/c last night, i only ram prime for 2hrs. Like I said, this is only a benchmarking o/c. It got me to 13th on the Custom PC leaderboard: Link

For 24/7 running I have the core V at 1.35 and QPI at 1.34v. This will let me run it at 208x21=4,368. Idle temps for this are just over 40, maxing out around 65. I also slow the ram down too. I run this at 6-6-6-15 @ 1T on 1.5v with it at 1,248mhz (208*6). This is prime stable for over 6 hours.

 

Very impressive Chris! If my C0 doesn't do well I might try and return it for a D0