***The Official Core i5 Overclocking Thread***

[JediFragger]

Nice1, thanks.

 

[iMacMart]

Hi Guys

With a Gigabyte GA-P55M-UD2 Intel P55 and aiming for 4GHz on a i5 750 overclock which is the best (but cheapest) DDR3 ram to get (4GB) to be able to achieve this?

Cooling wise I'm going for the Corsair H50-1 however I see some good results with air on here so that may change

Any advice please?

Thanks

 

[copystuff]

I have the same setup as vocch sitting at 4ghz all day and night. Glad i only paid £80 for my asrock p55 pro.

 

[inogen]

My new PC is coming together... All of it has not arrived yet, but I've started building... so I've started to wonder... I'm new to overclocking really - I did some years ago with a Athlon Thunderbird / Abit KT7a but I can't remember the half of it. Anyway. This is my kit :

i5 750 Lynnfield
Asus P7P55D motherboard
4gb (2x2Gb) G.Skill Eco 1.35v DDR3 12400 8-8-8-24

Thermalright True Black Cooler
3x 120mm Sharkoon 2400 rpm 81 CFM 37db fans
3x 120mm Akasa AK-174BK-S 17db fans
Scythe Kaze Server fan controller

It's all going in a Cooler Master Elite 341

I've bought three of each fan - the case takes 4 - one front, two sides and one rear. That leaves 2 for the CPU cooler if I need it. I'll be changing them around to find the best combo re: quietness and cooling.

I've read through a few pages of this thread and have some questions. I've read a few times that overclocking CPUs reduces their lifespan? Is this really true? Isn't it the heat and the heat / cold of powering up / powering down that shortens lifespan?

My Athlon still ran the last time I powered it up and that was overclocked the whole if it's life without a problem.

Also - what sort of speeds should I be aiming at with this set up? Is 4Ghz really going to fry my shiny new CPU in a year or so?!

If it does am I going to get away with RMAing it?

 

[Faztastic]

I have a core i5 750, and my motherboard is an asus p7p55d LE, i am on air, and using the Turbo VEVO tool it managed to clock it at 3.5ghz but i selected 3.3ghz for temperature as im on stock cooler. anyways.. i go to click cpuid and it says its at 1.4ghz :S now i know this is turbo boost.. but im wondering if my turbo boost will be at 3.3ghz when needed instead of the usual 3.2ghz. any idea..

Ram is corsair xms3, 4gig 9,9,9 24 stock. when clocked to 1600 its 9,11,11,24

 

[Rossdh]

I have a core i5 750, and my motherboard is an asus p7p55d LE, i am on air, and using the Turbo VEVO tool it managed to clock it at 3.5ghz but i selected 3.3ghz for temperature as im on stock cooler. anyways.. i go to click cpuid and it says its at 1.4ghz :S now i know this is turbo boost.. but im wondering if my turbo boost will be at 3.3ghz when needed instead of the usual 3.2ghz. any idea..

Ram is corsair xms3, 4gig 9,9,9 24 stock. when clocked to 1600 its 9,11,11,24

You've got Intel's Speed Step enabled. This will underclock the CPU when its full speed is not required. Run a game or a CPU intensive program and the speed will bump up to your selected speed.

 

[Faztastic]

You've got Intel's Speed Step enabled. This will underclock the CPU when its full speed is not required. Run a game or a CPU intensive program and the speed will bump up to your selected speed.

Thanks, is it best if i disable this feature in the bios would you say?

 

[Rossdh]

Thanks, is it best if i disable this feature in the bios would you say?

To be honest, I don't know. I'm a bit of a newbie to OC'ing myself, the i5 750 being my first, but I've got it disabled. In my bios, bare in mind my MB is a Gigabyte one so certain things might be under different names, I've got Turno Boost disabled, EIST (Speed Step) disabled, all C states disabled. All of those are power saving features and I've been told that leaving them on can cause some stability problems in the overclock.

 

[Mr Krugga]

Base clock - 189.5MHz
Multi - 19x

C-states, EIST - enabled

CPU clock - 3.6GHz
RAM clock - 1516MHz

Voltages:

Vcore - 1.276 V (CPU-Z shows 1.28 V idle and 1.208 V at load)
High Vdroop - (LLC off, don't like the voltage spikes and high temps)
VTT - 1.155 V (max safe spec. by Intel)
DRAM - 1.65 V (abs. max acc. to Intel)
PCH - 1.85 V
PLL - 1.054V

Ambient temp of 19*C
Stock V-core - 1.207 V
Zalman fan working at 1300rpm (barely heard)

Link to 3DMark Vantage results - http://forums.overclockers.co.uk/showpost.php?p=16241509&postcount=201

 

[gurusan]

What sort of IMC voltages are most people needing for 4GHz? Mine is not stable at 1.15V @ 4GHz, I need around 1.2ish. I see some people putting 1.4V? Seems way too high tbh

 

[Mr Krugga]

Anything over 1.2V is a risky deal, I wouldn't exceed this value over a long period of time (unless you do some pure benching that is). Some CPUs seem to get away with 200 bclk and 1.2V VTT/IMC, some will need a highly upped vcore to achieve 4GHz clock with this low uncore. I have IntelBurnTest stable at 190x20 with 1.26V vcore in BIOS (CPU-Z shows off 1.28V idle, 1.32 load) and 1.2V VTT - temps 25*C idle, 50-55*C load, 75*C full load IBT. This is with power savings options on as I want to get the most for the least. Will try to lower an uncore voltage now but I'm not expecting any major improvement upon the current voltage tbh.

The worst way to do a "safe" overclocking is to set voltages over Intel's absolute maximums or leave them on "auto" and pretend it's fine (whereas they actually exceed any limits).

My advice would be to set your CPU at 20x200, IMC/VTT to 1.21V (or anything below this value), PLL and PCH to anything in between the stock value and 5% increase in voltages, memory to its spec. Start from 1.25V with LLC enabled or 1.3V with it disabled, do 20 loops of maximum IntelBurnTest whilst controlling the temps in Core Temp (if they vary a lot, that can mean an unstable overclock as well) and vcore in CPU-Z. If you do run it successfully, run 3DMark Vantage and see if any problems occur (PCI-E controller is integrated with the CPU, right?). Up your vcore by 0.005-.01V any time you find it unstable until you get to a solid stable overclock. If you care about your bills, try turning on power saving options, do a proper testing as before and, or otherwise, try lowering your IMC/VTT till the system becomes unstable. Same applies to lowering the DRAM voltages which are also dangerous for your CPU (sic!) and PLL/PCH. The last two can usually be left on stock.

 

[gurusan]

Thanks for the advice. Just got to get used to this CPU...so far I love it though....here's a quick comparison as to how good the IMC is as opposed to the separate IMC on the i3 530.

i3 530 on the left, 2030MHz @ 9,9,9,27 (everest displays clarkdale timings wrong), i5 750 on the right 1000MHz @ 9,9,8,26.....massive difference!!!!

 

[Salami]

I know what you're saying about the VTT. I've got mine set to 1.18v at the moment and have a nice, stable 4Ghz with a decent core voltage too.

As nice as it'd be to get to 4.2Ghz I've found that exponential increases of VTT are needed to go past 4Ghz; with Intel's recommended maximums in mind I'm not willing to push it further at the moment.

Nice OC you have there, what does your vcore rise to under Prime95 / IBT?

 

[OpenToSuggestions]

Hey guys,

Please critique my overclock - I have dabbled in the past but this is my first 'major' overclock that I intend to run this speed 24/7. Rig in sig.

Base clock - 200mhz
Multi - 20x

C1E, Turbo Boost, CPU EIST - Disabled

CPU clock - 4ghz
RAM clock - 1600mhz

Voltages:

Vcore - 1.36875v
High Vdroop - LLC off due to hearing about voltage spikes
VTT - 1.17v
DRAM - 1.64v (manufacturer rates up to 1.65v for my ram)
PCH - Auto
PLL - Auto

Temps are fine. Running prime95 and IBT at the same time keeps it under 70. Have run IBT 25 times on max and prime overnight and all ok.
I have no idea about PCH and PLL. Also I have tried to put speedstep back on via the C1E and CPU EIST but the multi permanently stays at 20x according to cpu-z.

Also I have read that the safe max VTT is 1.21v, but on here I have read on the Intel link it is less than that - 1.115v? I tried 4.2ghz via the 21x multi at 1.43vcore I was nearly stable but one core hit 73 once in IBT which is above Intel's 72.7c (iirc of course) maximum.
My PCI is locked to 100mhz, if I changed this to say 105mhz, would this increase the bandwidth? (I ask because if I use sata3 or usb3 then it reduces my graphics bandwidth to 8x).
Any help/pointers much appreciated

 

[Mean Mr Mustard]

Nice OC you have there, what does your vcore rise to under Prime95 / IBT?

It goes up to around 1.296v, that's using LLC level 2.

 

[Mr Krugga]

Hey guys,

Please critique my overclock - I have dabbled in the past but this is my first 'major' overclock that I intend to run this speed 24/7. Rig in sig.

Base clock - 200mhz
Multi - 20x

C1E, Turbo Boost, CPU EIST - Disabled

CPU clock - 4ghz
RAM clock - 1600mhz

Voltages:

Vcore - 1.36875v
High Vdroop - LLC off due to hearing about voltage spikes
VTT - 1.17v
DRAM - 1.64v (manufacturer rates up to 1.65v for my ram)
PCH - Auto
PLL - Auto

Temps are fine. Running prime95 and IBT at the same time keeps it under 70. Have run IBT 25 times on max and prime overnight and all ok.
I have no idea about PCH and PLL. Also I have tried to put speedstep back on via the C1E and CPU EIST but the multi permanently stays at 20x according to cpu-z.

Also I have read that the safe max VTT is 1.21v, but on here I have read it is less than that? I tried 4.2ghz via the 21x multi at 1.43vcore I was nearly stable but one core hit 73 once in IBT which is above Intel's 72.7c (iirc of course) maximum.
Any help/pointers much appreciated

Sounds good to me, mine wouldn't do 4GHz with such a low voltage due to the board's vdroop. You can leave PCH and PLL on auto although I don't know if it's adjusted by your mobo when set to it. If you're not sure about it and want a full control over it, set it up to anything in between stock and Intel max. safe (PLL 1.89V, PCH 1.1V).

1.21V for VTT is absolute max. which isn't considered a safe voltage for the CPU's lifespan but shouldn't damage it. Max safe is 1.155V.

Thermal Specification: The thermal specification shown is the maximum case temperature at the maximum Thermal Design Power (TDP) value for that processor. It is measured at the geometric center on the topside of the processor integrated heat spreader. For processors without integrated heat spreaders such as mobile processors, the thermal specification is referred to as the junction temperature (Tj). The maximum junction temperature is defined by an activation of the processor Intel® Thermal Monitor. The Intel Thermal Monitor’s automatic mode is used to indicate that the maximum TJ has been reached.

Stock cooler goes over 70*C normally, you shouldn't worry about anything below 75*C under full load of running IBT/prime95.

I haven't touched PCI controller but in theory, higher frequency should increase its bandwidth (and sometimes stability).

 

[OpenToSuggestions]

Mr Krugga: Thanks for the help already given!

I get bsod if I lower my VTT to 1.15 (currently 1.17v).

I set my PCH and PLL to stock and I got an IBT fail after 2 runs (so really not far off stable). I am currently trying 1.12v PCH (my motherboard's smallest step up over 1.05v)and 1.86v PLL - IBT is running 25 times at max and all OK halfway through The crazy thing is that the PCH bios settings range from 1.0-2.0v on my board!

Are these actually related to the cpu or are they motherboard voltages?
Also my ram voltage of 1.64v I chose as my G.Skill ram is rated at 1.65v. If the manufacturer rates this then surely this voltage can be completely safe or they would get screwed with rma's? Does the ram voltage have any impact on the cpu on the i5 platform?

Are these Intel 'max safe' and 'absolute max safe' voltages new or have they always released such data on cpu's?
Obviously I have just blown several hundred pounds on my setup and don't want it to be damaged/degraded in 2 years time due to overclocking (reducing the cpu life span from 15 years to say 8 years is no concern though as it will be chucked away way before that!).

EDIT: If many people have been running i5 750's at VTT 1.25v for a few months now without degradation then surely running at 1.21v is going to be fine long term? I am starting to think that Intel have been massively conservative with the voltages, almost as over the top as psu requirements for a graphics card.

 

[Mr Krugga]

You're doing 4GHz overclocking, I think applying over 1.155V to the VTT is expected to say the least. It's strange that your mobo does not let you adjust PCH voltage in small steps, I thought this Gigabyte board is a clever overclocker Maybe there is a new BIOS version fixing this little issue? I wouldn't worry about using 1.12V as your PCH volt but it's still an issue for anyone willing to overclock safely. I'm not agreeing with the following article in a few things they suggest but they seem to explain what PLL and PCH are and do relatively well - http://www.bit-tech.net/hardware/cpus/2009/09/21/overclocking-intel-s-core-i5-750/2. You may find some bits out of this guide useful to your overclocking as well. I strongly suggest not to exceed Intel's absolute maximum voltages anyway.

CPU PLL voltage (phase locked loop - a feedback control system that automatically adjusts the phase of a locally generated signal to match the phase of an input signal)

Yes, DRAM voltage definitely does have an impact on the Lynnfields - its strictly related to the on-die DRAM controller. Anything over 1.65V, even a small voltage adjustment such as 0.05V may damage your CPU. Although it's only used to get a stable overclock on your RAM (in this and any other case involving RAM sticks designed to run on Lynnfields, they are overclocked RAM kits and applying 1.65V to them is actually an overclocking), the difference between DRAM voltage and VTT/IMC (uncore) must not be greater than 0.5V. That's why it's considered dangerous to run your RAM at 1.65V when you only apply a stock voltage to the uncore of the CPU (which would be around 1.1V). Many RAM manufacturers tend to advice overvolting a VTT to over 1.3V which can surely be a killer for the CPU. Default voltage for DRAM is 1.5V and that's what all RAM kits should be able to run at, although they are rated at their overclocked settings.

You may be concerned about i5/i7s going strongly with over 1.21V (absolute max. according to Intel) on vcore however you should be aware that degradation process often takes years, not months. Even though Intel may seem to be conservative with voltages, bear in mind they advice to stay within 1.4V safe applied to vcore and 1.55V as the absolute max. This is certainly more than most overclockers, who use their PCs over the years, would do for 24/7 use and yet these people apply more than the absolute max for VTT is to their CPUs because they are either non-aware of the new specs for Lynnfields (which differ from Bloomfields because of the on-die controller) or are brave enough to play with their luck. You can't tell for sure that exceeding Intel's absolute max voltages is safe as processors based on this architecture haven't been out for more than a year.

With that said, I think 1.21V may slightly reduce your CPU's lifespan but as long as you provide it a good cooling, you shall enjoy it for several years.

 

[OpenToSuggestions]

Please ignore this post, I just got a reset on a game so am not stable with the new voltages I tried.

 

[OpenToSuggestions]

Mr Krugga: Many thanks for the help so far

I have the following settings:

Base clock - 200mhz
Multi - 20x

C1E, Turbo Boost, CPU EIST - Disabled

CPU clock - 4ghz
RAM clock - 1600mhz

Voltages:

Vcore - 1.36875v
LLC - off due to hearing about voltage spikes
VTT - 1.17v (1.15v causes bsod)
DRAM - 1.60v (manufacturer rates up to 1.65v for my ram. Despite passing memtest, IBT and Prime, at 1.5v I got a bsod upon loading a map on bad company 2. The G.SKill website says 1.6 volts even though the sticker on the sticvks says 1.65v)
PCH - 1.12v (1.05v causes IBT error. 1.12v is the smallest increment over 1.05v)
PLL - 1.80v (normal voltage)
PCIE - 100mhz.

I agree with you, my does have slightly odd voltage increments in some areas! I do have the latest bios. Comments please.