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

I've overclocked my i5 in few ways now. All pretty well - i've had it upto 4ghz+ and back down again.

To be honest I can't find any real world performance gains. I mainly use my PC for programming - some photoshop and the occasional gaming session (where perhaps I might be getting some gain)

What about underclocking? Looking for energy savings and less stress on components / noise levels?
 
Hi Everyone,

Well got to a point with my i5 750 overclock that makes me really happy and thanks to lots of people on these forums and a few from other sources i think its job done.

Below i will outline the settings used to get the 4gig overclock and there should be a pic of the 8hrs 20 min prime blend run to show its stable.

I have the following kit, so if you have the same MB then this should really help, "well i hope so." :). You will see i went for a slower clock on the memory but with tighter timings seems to work better for the system.

Intel i5 750
Gigabyte P55A-UD4
OCZ 4gig obsidian


MB Tweaker
Advanced Frequency Settings

CPU clock ratio "20x"
QPI clock ratio "32x"
base clock control "Enabled"
BCLK Frequecy "200"
system memory mutli "6" (this gives 1200) set timings to 7-7-7-20 1T
PCI Express "100"
C.I.A.2 "Disabled"

CPU Clock drive "900"
PCI Clock Drive "900"

Advance CPU Core Features
Turbo "Disabled"
Cores "all"
everything else "disabled"

MB Tweaker
Advance Voltage

Load line "Enabled"
CPU Vcore "1.2875"
QPI/VTT Voltage "1.21"
PCH Core "1.14"
CPU PLL "1.88"
Dram Voltage "1.66"

Everything else auto.


Here is the pic & thanks again to all that helped,

 
Last edited:
LongThumb said:
Dunno if it's really classed as overclocking.

Got my i5 at 2.66Ghz (stock) and running @ 944mV. Never goes above 50c in IBT.

And if i'm honest I haven't seen the difference in speed over 3.6Ghz @ 1.184v.
Click to expand...

That's cool. I can't tell the diff between mine @ stock or 4Ghz - I think my bottleneck is my HDD (500GB WD green).

I've settled down @ 3.4Ghz, 1.04v Core - @ a pretty constant 39c. Temps don't really seem to come down if I drop the multiplier or bclk so I'm quite happy there for the time being. I think my next job is cable management and fan arrangement to try and lower the temps - everywhere is 35-40c regardless of what I seem to use the PC for day to day... I reckon I can get that down a bit. Then I'll see what clocks I can vs temps.

I don't know what I'm doing though ;) All seems quite different from overclocking my athlon thunderbird back in the day. I've been on a laptop since. Back then any overclock gave quite easy to see increases in speed for apps like Photoshop and Outlook. Not any more!

I do know If I'm using more power and generating more heat I want tangible differences in application speed / responsiveness.
 
Could you guys try running the 3dmark05 cpu tests.....I've found that although these other tests show the cpu to be stable, this test will hang on a less than perfect overclock.
 
can i just ask out of curiosity, whats the highest oc any1 has achieved on stock volts? i've managed 3.4ghz with load/stress temps hovering around 60c on prime95 (5 hours approx) and on IBT low 60's (20 runs)
 
On the subject of the maximum recommended voltage of the VTT being 1.21, if I set my board to auto it will set the VTT 1.35-1.4, Prime95 will run stable, if I set it fixed to 1.21 I get blue screens constantly which are alleviated around 1.3 -- have I just got a bad chip that won't take a 200MHz BCLK or are others finding they have to go above 1.21 to get it stable?
 
Spektor said:
On the subject of the maximum recommended voltage of the VTT being 1.21, if I set my board to auto it will set the VTT 1.35-1.4, Prime95 will run stable, if I set it fixed to 1.21 I get blue screens constantly which are alleviated around 1.3 -- have I just got a bad chip that won't take a 200MHz BCLK or are others finding they have to go above 1.21 to get it stable?
Click to expand...

My chip wouldn't do 4GHz stable without a lot of VTT voltage pushed through it thus I don't play with it (until I get my hands on a watercooling setup). I'd advice to stay within the Intel's specs although if you can afford the risks and need a 4GHz performance, go for it.


Thekwango said:
can i just ask out of curiosity, whats the highest oc any1 has achieved on stock volts? i've managed 3.4ghz with load/stress temps hovering around 60c on prime95 (5 hours approx) and on IBT low 60's (20 runs)
Click to expand...

I managed 3.6GHz with temps at 50*C under load. Voltage set to 1.188V in BIOS, 1.2V idle, 1.23V prime load (LLC on). I have to disable C-states to get it stable though (as well as Turbo, obviously).
 
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Mr Krugga said:
My chip wouldn't do 4GHz stable without a lot of VTT voltage pushed through it thus I don't play with it (until I get my hands on a watercooling setup). I'd advice to stay within the Intel's specs although if you can afford the risks and need a 4GHz performance, go for it.
Click to expand...

Yeah I'm thinking of just dropping to 3.8GHz, which runs stable with a 1.28 vcore and apparently fine at 1.21 vtt (done about an hour of prime so far on that) -- but 4GHz requires 1.38v and a 1.3+ vtt. 200MHz isn't worth it but still, would have been nice to get that nice round 4 :(
 
Picked up a 2nd hand i5 750, mobo & RAM the other day.

Was running 4GHz @ 1.35 Vcore & 1.225 VTT and that was with LLC on. Was prime stable but running IBT on the higher settings would cause it to fail. Temps were high too, reaching over 80c when running IBT (Corsair H50 standard fan setup).

Decided to reset to stock settings and work my way up myself. Worked up to 3.8GHz (190x20) @ 1.3125 Vcore & 1.175 VTT which was hitting 70c IBT max. That was with LLC off.

Also tried enabling C1E, Speedstep & turbo and got it stable with 1 notch more Vcore. So 3.99GHz (190x21) @ 1.325 Vcore & 1.175 VTT. 72c IBT max temps on that one.

Left PCH & PLL at standard settings for all.

Gonna have another play about though and see what can be achieved. Not that impressed with the H50 though so prob won't push it too high.
 
currently playing around with this new i5 cpu i got with the giga p55m-ud4 mobo and 4gigs of corsair value ram.

just getting a feel for the cpu and seeing how to test it properly for stability and work out best strategy for overclocking.

results so far show prime95 is as usual a load of crap for cpu testing. linpak is what i will be using for all further testing with this cpu.

primestress.png


3 day prime test passed,

then ran linpak straight after:

linpakfail.png



currently iv worked out how to use the 21x multi as a permanent multiplier with speedstep enabled, so insted of multipliers going from 9-20 they will go from 9-21, and single and dual core loading will still not exceed 21x multi (before they were going up to 24x)

so far testing is going at 3.8ghz but i suspect this chip i got is not a good clocker, will see though since im now testing with 1.325v at 3.8ghz. will see if it last the 72 hour linpak test.

what i do know about this cpu is that its 3.5ghz stable using stock voltages turbo disabled 175x20 and thats using stock vtt volts too. but going over 175 block seems to want a lot of vtt volt bump, 181bclk testing is being done using 1.19v vtt.

oh cooler i using is zalman 10x flex with scythe sflex1200 fan.

will keep this thread updated with progress if required.
 
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no good, linx failed just after 27 hours at 3.8ghz,

linxfail38ghz.png



settings used were:

memory is on 8x multi, 1448mhz memtested for 24 hours and passed 9-9-9-24 1.5v set in bios, shows as 1.55v

181x21 = 3801mhz
1.32500v core
1.190v vtt

all other voltages set to normal.

any suggestions on what to do to make stable?
 
Cyber-Mav said:
any suggestions on what to do to make stable?
Click to expand...

More volts - simples. Especially on vtt if you're trying to get the bclk up towards 200. I have a UD5 mobo and find it best to have LLC on level 2 or I suffer droop under load. How were your temps during that last run?

Can I ask what your intended use of the rig is? Your criteria for stability seems... um, demanding!
 
machine is used for video encoding and mostly playing crysis wars online and at lan party. also some need for speed shift is played at lan party too.

any crash from the machine during gaming will result in utter wee-take so it has to be proper stable.

since i only have 4gb ram its harder to test the cpu, linpak only loads the cpu for just under 2 mins per pass at 3.8ghz, so its taking much longer for me to stability test.

will try again upping the core voltage a bit more, as you can see even 27 hour linpak is not a good enough test with only 4gig system ram. need minimum 72 hour linpak stability.

max temps cpu got to was around 73c on 2 of the cores, other 2 cores seem to sit 4c lower.

edit:crysis wars minimised itself saying system was runninng low on ram so i guess i may just stick the system back to 3.5ghz and get 8gig ram in the system and then try clocking up again.
 
Dunno what memory you have there but try upping its voltage to 1.6-1.65V, PLL to 1.9V and PCH to 1.1V.

You should also try increasing VTT to 1.22-1.25V if you want to push bclk any further.

As long as you can keep the temps below 80*C in Linpack, you should be fine :)
 
gonna stick back to 3.5ghz now and get 4 more gigs of ram, need 8 gig these days. once i got more memory in i will continue overclock testing.
 
Lleot said:
Isn't 27 hours stable enough?
Click to expand...

nop, in the reality of it, the cpu shoudl be able to run linx 24/7 for years without making any errors. but doubt anyone is gonna stress test for that long.
lol imagine that you buy a 6 core cpu overclock it and then stress test it for 2 years, then finally it passes the tests and your ready to use it for some gaming, only to see that its too slow to run squat now. :p


the screenshot i posted in the earlier post shows that somewhere down the line a 1 or a 0 has turned into vice-versa and thats an error. to me thats unacceptable. it has to be 100% error free for a minimum of 72 hours before i use it for daily use. heck i only overclock once, and then test it. 3 days is not much to ask for when its gonna be running for the rest of its life in its overclocked state.

but as mentioned before the error i got is most likley memory or memory controller related. although the ram passed memtesting overnight the memory controller (imc) is the tricky one to hit during stress testing. even 3 days of prime blend did not catch any errors on it.

i gone back to my safe settings of 3.5ghz last test screenshot i did is here:
i575035ghzstable.png


its still going into its 4th day with no errors in linx, i doubt any will occur since the bus speed is fairly low and ram is running at its rated speed. at 3.8ghz the ram was running overclocked and it may have needed more than an overnight memtest to catch any errors.

gonna look into getting more memory since 4gb is not enough these days.
 
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