Can't reach 4Ghz. only 3.8Ghz for i7 on P6T (help pls)

[OCD007]

Hi

I am having problems achieving a stable 4 Ghz OC

System Spec

i7 920 co TRUE 120

Asus P6T

6GB Corsair XMS3 1600

HD 4870 1 GB

Toughpower 750W

Antec 900

OVERCLOCKING RESULTS



These are all stable overclocks @ the minimum voltages I could achieve

Speed step and Turbo are enabled

and all other settings are set to auto.

I have tried various combination's of Base clock and multiplier

and took the cpu and qpi voltage up to 1.5 volts but I cannot get

a stable 4 Ghz OC unless I turn off HT.

















Could anyone suggest changing the other settings, IOH, pll etc or any suggestions

at all would be appreciated.

Thanks

 

[thestepster]

disable speed step mate thats a power savin feature we dont need that for overclockin

and your rams 1.65v u will have to set it as 1.66 in the bios cause if its not gettin enuff juice and thats gonna cause stability issues, you dont undervolt your ram

 

[OCD007]

Thanks for the reply

I have disabled speed step and lowered all multipliers and the best stable Base clock I can achieve seems to be 195 (seems low ?). I have tried up to 220

195 x 14 = stable

195 x 20 = BSOD

My highest overclock I have managed to achieve is 4 Ghz BUT that is only with HT turned OFF

191 x 21

cpu 1.45

qpi 1.475

Dram 1.66

speedstep disabled

Turbo disabled

C1E disabled

Linx max Temp 77 C

Why would this be unstable with HT turned ON?

 

[thestepster]

lookin more at it mate i totally didnt notice your cpu is a c0 stepping this is the reason y its not a good overclocker, most d0's will hit 4ghz all day but im afraid it was rare for a c0 to do it cause it needed much more volts to do lower clocks

sorry for the confusion mate

 

[tinytomlogan]

Yeah a quick look at the results and info you have given looks like its just a below average cpu tbh. At 1.45v you should have got 200bclk already.

IMHO dude get the volts down to 1.4 as thats going to be well hot as it is and just go with what ever the max stable you can get. Then hold fire till you can afford a 950.

 

[OCD007]

Thanks for the feedback guys

Im not to bothered about having a 4 Ghz PC, Im just happy to have had it confirmed that this is how far this system will go and there's no other tweaks to try. Although I was hoping Because it's been fun trying

As you can see from my benchmark results it doesn't gain much performance over the 3.6 Ghz mark, especially compared to the voltage and heat increase.

Also at this speed I have just found that the memory will overclock to 1720 Mhz but I have to increase the QPI to 1.5v

So for a 24/7 usage I will set it as follows

172 x 21 @ 3440Mhz ( @ 3600Mhz with Turbo )

CPU 1.325 v

QPI 1.5 v

Dram 1.66v @ 1720 Mhz 999-24

Do you think the QPI @ 1.5 v will be ok for 24/7 usage?

If I lower the ram to 1376 Mhz I only need 1.35 v QPI

 

[tinytomlogan]

QPI is fine, I need 1.525 for 2000mhz ram on pretty much every 1366 CPU Ive ever touched, so I wouldnt worry fella

Now you know you cant go mega high it would be worth you getting some Mushkin 1600mhz 6-8-6-24 Ram so you can have nice tight times instead of all out MHZ, its very good ram and Id deffo recomend it for your system.

 

[OCD007]

LOL , TTL are you going to try and sell me something every time I post?

If I was Building a complete new system I would go with every one of your suggestions but right now I am happy with the speed of my RIG and just learning how it works and finding out the best it can do

Its fantastic to know Im safe @ 5v QPI (thankyou)and to be honest if I was going to spend a bulk of money on this system it would probably be in the graphics department but that won't be for some time.

I hope this doesn't seem ungrateful , because I am grateful and absolutely chuffed to be speaking to the Guvnor

As for RAM performance, I have downloaded Aida 64 from your site and done a few benchmarks with various cpu speeds, memory speeds and timings.

MEMORY RESULTS



Uploaded with ImageShack.us

I have concluded that tighter timings will improve the latency but not have a massive effect on the Read/Write speeds.

And Increasing memory speed will increase both latency and R/W speeds.

Also increasing CPU speeds will increase them both.

And I got totally confused when I went from 1720 Mhz to 1750 Mhz and the R/W speeds got worse but the latency improved dramatically, does this make any sense?

What are the different benefits between Latency and R/W speeds in real world applications ?

 

[tinytomlogan]

ahhh but 1600mhz at cas6 would be even quicker still

If you are happy where you are then stick there dude, when perf dropped it will be because they were borederline unstable.

 

[OCD007]

LOL Cheers TTL £ 150 and I could make higher graphs

Id more likely spend that on a GTX 460 1 GB

Congrats on your million

 

[OCD007]

Well, I finally got 4 GHz with HT enabled

Here are the settings ( i7 920 C0 )

21 X 191

Turbo, speedstep, C1E, CPU and PCI Spread Spectrum ALL Disabled

RAM 1528 MHz

CPU Vcore 1.45v

CPU PLL 1.92v

QPI 1.475v

IOH 1.28v

ICH 1.2v

vdimm 1.64v

Obviously not a 24/7 OC, but good enough to do some benching.

http://valid.canardpc.com/show_oc.php?id=1671322

 

[tinytomlogan]

You want to aim for 200x20 dude, get that tied in with 1600mhz ram then nudge up to 2000 if your ram will take it.

Probs need more QPI if you want to run your UCKL at twice the mem speed. Also nudge the Ram up to 1.66v