i3 540 overclocking question

[Gustavus]

I have an i3 540 on a Gigabyte H55M-UD2H motherboard overclocked stably to 4011.6 MHz; 21x 191MHz. Air cooled with a Cooler Master 212.

To do that I had to raise Vcore to 1.328 volts. As I said it is stable and has been running with these settings for nearly a year. I had hoped for better, but this is what I have.

My question concerns the QPI link. It shows as 4202.5 MHz which is considerably higher than what I see in other peoples posts of specs for their i3 540 systems. Is this a problem, and if I could reduce this could I expect to acheive higher speeds?

Thanks.

 

[SPBHM]

I have no experience with clarkdale, but if you look here Anand also had some pretty high QPI when overclocking http://www.anandtech.com/show/2901/14
(i5 6xx and i3 5xx are the same thing),

now your MB uses the H55, which is probably a more basic model? so I could see the MB having trouble to work with the BCLK much higher than 191, considering the default is 133 right?

also it might be something related to memory clock?

 

[Gustavus]

SPBHM
Thanks for the reply. I learned something from the link you gave -- that the CPU clock and the QPI link should be as close as possible. Maybe my 4 GHz and 4.2 GHz are not so out of synch after all.

Memory is fine. I have GSkill ripjaws 1600 and have set the multiplier so it is safely in spec.

I realize overclocking is always something of a crapshoot, but had hoped to get to 4.2 GHz with this rig and have sort of gnashed my teeth for a year since so many reports of even better results with this MB and CPU have been posted.

 

[Blastman]

Some of the early versions of 1156 H55 MB's had the GPU coupled to the BCLK.

I have a H55M-UD2H with BIOS F4 and I'm pretty sure when you up the BCLK you are overclocking the GPU also. I believe the later versions of BIOS decouple the GPU from the BCLK. At 4.0Ghz, a BCLK of 182/133 x 733 (default graphics speed on i3-540) = 1003MHz which is about as fast as you will go, so you may by GPU limited with your overclock.

I used to be able to get a little over 4.0Ghz, but now I can only get to 3.8Ghz before I start crashing, so my GPU won't even run as fast as it used to.

So check your BIOS version and see if it needs updating. Which reminds me, I need to upgrade my BIOS -- just haven't bothered yet.

 

[Gustavus]

Blastman,

Thanks for the reply. I use a PCIex MSI graphics card and have the onboard GPU disabled. I also have the F4 BIOS. I was able to boot at 4.2 GHz back when I was doing the initial overclocking, but it wasn't stable there and would crash running Prime95. As I said it is stable at 4.0 so guess I should be content.

I am a mathematician and actually use the computing power. I have a graph backtracking routine that runs for hours -- backtracking grows exponentially as you know.

 

[tweakboy]

SPBHM
Thanks for the reply. I learned something from the link you gave -- that the CPU clock and the QPI link should be as close as possible. Maybe my 4 GHz and 4.2 GHz are not so out of synch after all.

Memory is fine. I have GSkill ripjaws 1600 and have set the multiplier so it is safely in spec.

I realize overclocking is always something of a crapshoot, but had hoped to get to 4.2 GHz with this rig and have sort of gnashed my teeth for a year since so many reports of even better results with this MB and CPU have been posted.

Hang in there brother.. its ok........ youll hit 4.2Ghz its a setting away!

 

[Blastman]

My question concerns the QPI link. It shows as 4202.5 MHz which is considerably higher than what I see in other peoples posts of specs for their i3 540 systems. Is this a problem, and if I could reduce this could I expect to acheive higher speeds?

That definitely seems too high for the QPI.

Are you using the AUTO setting for the QPI? If so, it really shouldn't be running that fast. I tried a couple of quick overclock settings on my MB with QPI on AUTO …

Stock 133, CPU = 2.93GHz, QPI = 2933.6
BCLK 150, CPU = 3.3GHz, QPI = 3300.5
BCLK 170, CPU = 3.74GHz, QPI = 2720.5

So as I overclock, the AUTO adjusts the QPI to keep it somewhat close to 2.93GHz. 4202.5 seems way high and could be limiting your overclocks.

On the other hand 4.0GHz is not a bad number for Clarkdales. You might push up to 4.4 or so with more tweaking and shutting off things like the CPU idle states (like CPU Enhanced Halt C1E), increasing QPI voltage …etc., but you will only gain another 10% or so in performance. At 4.0GHz you already have over 30% so that's not too bad -- there isn't too much more on the table left to get. But if you want some more speed you might try manually setting the QPI if the AUTO is not cooperating or try upgrading the BIOS to a later version.

 

[Gustavus]

Blastman,

Thanks. I spent today working on a mathematics paper -- had an insight on how to do something I had not been able to figure out until now. So it was a case of strike while the iron is hot. Didn't touch the computer today -- except to do calculations that is.

I just noticed you and I joined AnandTech at the same time, Oct 1999. and have almost exactly the same number of posts. Quite a coincidence.

 

[Blastman]

I just noticed you and I joined AnandTech at the same time, Oct 1999. and have almost exactly the same number of posts. Quite a coincidence.

Ya, I noticed that too. -- and the same MB and Clarkdale CPU.:biggrin:

 

[Gustavus]

Blastman,

Finally got back to check on the system. QPI is set on auto. Don't know why I have such a high reading compared to what I have seen on numerous postings for other peoples system specs.

Won't mess with it any more since it works. Am putting together a new system based on a EVGA Z69 STW motherboard and an Intel i5 2500K CPU with a humungous Cooler Master V6 GT cooler. Should get well over the 4 GHz boundary this time. This will probably be the last computer I build. I am 82 and my eyesight is getting too poor for fine work anymore. Has been fun though.