GA-P55M-UD2, i5-750, overclocking help needed for a veteran.

Heya all

This is not my computer, I'm building it for my aunt and her family, and I want to give them a fast, stable system after living on a slow windows 2000 era computer until now.

I'm doing some research on what things need to happen, and settings that need to be set on these new motherboards to keep the chips stable.

I am perusing the forums for info but I put this up in case anyone has anything links or advise to point me in the right direction.


I havn't overclocked any of these new intel chips yet, I had it at 3.8 ghz before it bluescreened just upping the bclk with everything on auto and making sure the memory stayed around 1333. I dialed it down to 3.5 and it seemed fine, then froze during a online video. so I dialed it down to 3.33, and still the other day I had an issue with it, so now its back to stock settings till i do more research on overclocking these chips.


I guess my main question is, what voltage settings should i target as my main targets, and what are the voltage ranges for my processor for those settings.

i know the main one from here.
http://processorfinder.intel.com/details.aspx?sSpec=SLBLC


but what else do i need to take into consideration? im still reading up on it right now but links would be awesome


windows 7 64bit ultimate.

my memory is CT2KIT25664BA1339

2gb ddr3-1333 1.5V

motherboard/processor
GA-P55M-UD2, i5-750

Heatsink
Noctua NH-U12P SE 2
IC Diamond thermal paste.

GPU
4850 1gb

Power Supply (Yes I know, not the greatest brand, but hey, I was trying to keep everything in a budget of 650$ and its rails are totaly decent)
SUNBEAM|PSU-ECO650-US

Case
antec 300

Well, I have a pretty much identical setup (UD3 Mobo with 2GB 1333 Kingston Ram), and I found that Setting the vCore to 1.4, QPI/Vtt to 1.31 and the ram to 1.5 allowed me to get a 4GHz 24 Hour P95 Stable system. As to get the ram stable, I went with a 6.0 Ram Multiplier and tighter timings rather than a 8.0 and looser timings.

I would go for a 175*20 Bclock to start and see how far you can get it with those (or lower, I managed to get 4GHz to boot to W7 Ultimate x64 at a vCore of 1.264v, didn't like anything more than 10% load tho )

You remembered to get the latest Bios (http://www.giga-byte.com/Support/Motherboard/BIOS_Model.aspx?ProductID=3165 Version 4fg)?

YMMV of course and you might have just gotten a crap OCing chip.

I understand wanting to see how well you can overclock this but if it really is for your aunt why mess with it at all? An i5 system at stock setting will be fast enough for anything a normal family throws at it and you won’t have to worry about anything.

asking why im overclocking on on overclocking forums seems slightly silly, but to answer your question, im overclocking it because,

1. im finding out if any parts are faulty and/or if voltage settings need to be changed in order for the system to be stable. and giving them a very fast, stable computer.

2. they most likely will get a computer faster than you can buy at stock processor speeds, and thus get way more performance and value for thier money

3. its not just for my aunt, its for my cousins too, hence the gaming videocard with a GB of ram, and she does photoshop too so. The speed difference does make a difference.

at 3.6Ghz its more than a 33% improvement.





anyway on with my overclocking details!


Set all voltage values to normal so they would not be on auto. lowered the multi on the qpi/vtt turned all power saving features off, never found spread spectrum.
Set to overclocking bit by bit as i was playing left 4 dead windowed, and running prime 95 64bit on blend with the check rounding errors option checked, whilst monitoring my temps via coretemp, my cpu via cpu-z, my videocard temps via the catylist control center, and upping the BCLK live with easytune 6. Got to 3Ghz before it failed at 3.1Ghz Temps have not gotten into the 60's Celcius under load.

Original BCLK = 133 x 20 = 2.66Ghz
CLOCK = 3GHZ
BCLK = 150
Vcore = 1.2625v
VTT = 1.1v
PCH = 1.05v
PLL = 1.8v


since the vcore I had seen was high in auto (near 1.4 something like 1.36-3.8) still fail/freeze during normal use at 3.33 ghz but boot all the way to 3.8 i decided to up the vtt a tiny bit to 1.17 and see what gain i could get. and I made it to 3.2 ghz before failing at 3.3Ghz
CLOCK = 3.2GHZ
BCLK = 160
Vcore = 1.2625v
VTT = 1.17v
PCH = 1.05v
PLL = 1.8v


increased the vtt to 1.210, typed upthe other two comments and then wrote this and played abit with prime going. but it wouldnt let me live update the clock for some reason, was saying it was too fast

CLOCK = 3.3GHZ
BCLK = 165
Vcore = 1.2625v
VTT = 1.210v
PCH = 1.05v
PLL = 1.8v



so instead i rebooted and since theres some serious droop goin on on the vcore, i went ahead and increased it, at idle its still only at 1.232 instead of the 1.26875 that i raised it to. raise clock speed to 3.5 and am testing now at load and during gaming vcore fluctuated between 1.184 and 1.2, so i am going to raise it more since the system obviously liked the extra juice as it ran stable at 3.5 and id like to have it at load, at least be equal to the vtt if only to match

CLOCK = 3.5GHZ
BCLK = 175
Vcore = 1.26875
VTT = 1.210v
PCH = 1.05v
PLL = 1.8v


Upped the clockspeed to 3.7Ghz, Increased the Vcore to 1.29375 (still showing between 1.248 and 1.232 at idle,) Failed a prime.
increased vcore to 1.3125 , showing 1.264 at idle. 1.232 and 1.216 at load.
played a level of L4D with prime running.
thinks to himself.. probly shold have increased the vtt... wait i will!


CLOCK = 3.7GHZ
BCLK = 185
Vcore = 1.3125
VTT = 1.210v
PCH = 1.05v
PLL = 1.8v


so i decided that the vtt probly needed a bit more juice at this point, so i went ahead and gave it a bit more (1.250) and upped the clock speed to 3.9 , failed immidiately on the prime.
upped vtt to 1.310 still failed immidiately.
put vtt to 1.250 again and upped vcore to 1.35 still immidiate fail.
so until i get more advice on acceptable voltage ranges for the settings, i have cranked it back down to

CLOCK = 3.5GHZ
BCLK = 175
Vcore = 1.26875
VTT = 1.210v
PCH = 1.05v
PLL = 1.8v

ill test this and make sure its stable. and wait to hear from anyone or find more data myself.


no i havnt updated the bios since on the first attempt with the stock cooler i booted at 3.8, didnt want to mess with the bios till i overclocked everything properly.

Have you tried enabling turbo mode to get the x21 multi?
How about testing 172x21 ~3.6 Ghz with your last settings:

CLOCK = 3.6GHZ
BCLK = 172x21
Vcore = 1.26875
VTT = 1.210v
PCH = 1.05v
PLL = 1.8v

3.6Ghz is a nice low voltage overclock for an i5 750. I would think you could also perhaps manage a 3.8Ghz overclock with some more voltage but I don't think anything higher would be suitable for your Aunt and cousins who I assume are not overclockers.

The reason why I said to update the bios is because the new bios improves the OC ability apparently

my turbo mode does all kinds of funky things. i saw it jump to 23 multi once for a moment in cpu-z. if i could actually set the multi to always be 21 i would do it. but I dont like the processor constantly changing processor speeds and voltage, it makes it much more difficult to make stable in my opinion. when you have to take into account a processor suddenly jumping in clock speeds from like 1.2GHZ to 3.6GHZ, as well as going from a low voltage to a high one suddenly anytime they mini a game and go back to it. id much rather find a comfortable voltage and speed for the processor and just leave it there, who cares if the processor didnt need to be running that speed, when its stable and reasonably speeded and volted.

You should be able to lock in your x21 multi (4 threads) through BIOS so that it always runs at 3.6. With C-State "enabled" is where the cpu will allow the x24 multi to work for up to two threads.

i cant stress enough to not push this board to far... i tried to get my i7 860 to 3.8ghz stable but the board killed it self while priming. same parts from the P55M-UD2 went into a P55M-UD4, what do you ya know, 3.8ghz prime/orthos stable.

rodger, thanks.

what voltages frequency did you kill it at?

only voltage i upped was [email protected] actual and bclk was at 200...

wow, then you think the voltages im running are too high eh?

i was running it at 3.33 with a 8 multi and a ramspeed of 1333 which its rated for, but the computer had an error, i think the memory isnt able to run to spec which is why it prefers 3.5 at a 6 multi for the ram. ill keep the voltages down, but i think that the vtt definately helped out stability, do you happen to know what the vtt is rated to take?

ill have to run memtest on it... sigh, that means ill have to burn a new disk...

no i dont know what its safe max is, i just left all voltages on auto. i was able as you can see by the link in my sig, to 220 Bclk on the first bios release.

I still think 3.6 is a sweet spot for the i5 with just low voltage bumps above stock settings.
Here is mine with the turbo (x21) multi locked in.

on auto the board cranked the vcore extremely high for me. it was running in the mid to upper 1.3V range getting really close to 1.4 and that is taking into account vdroop! i was fairly certain at one point that the auto setting on the board had set it to 1.4Vcore. and it was just vdrooping

thats why i took the auto settings off.

also, can you actually lock the multi at 21? or does it fluctuate between 20 and 21?

i guess i did turn turbo mode an eist off at the same time, maybe if i just enable turbo mode it will lock it.

On my board I can lock the x21 multi in. I manually set all my voltages in BIOS... none are on default/auto so they won't rise with the increased BCLK. At 3.6 I have just small bumps to Vcore: 1.25625v, Vtt: 1.125v, DIMM: 1.55v.

The lock definately works, as long as turbo mode is set to enabled the 21 multi is enabled. you can even see it in the bios (not the 21 multi but the actual clockspeed)
with turbo on, its running at 21 multi even in the bios. and cpu-z see's it as 21 also.

I'm re testing right now, i ran memtest with my settings at 3.33GHZ 20 x 166 with my setting at

vtt 1.210

vcore 1.268

ram is set at 1.5 which the ram is speced for.

everything works so im working with the 21 multi now with prime to see where its stable.

3.5Ghz (21 x 167) while running the ram at its rated speed 1333 (1336 really) with just an increased multi and a very slight bclk increase for nearly a ghz overclock that im sure will be no problem running stable. since I hade 3.7 (20 x185) prime stable during multicore videogaming like left for dead.


im definatly going to try to lower the vtt and im going to add another 4 gigs of ram before im done so we will see a comparison of required voltage to get 3.5 stable with 4 dimms vs 2 dimms(ram sticks for you laymans )


EDIT: the 1333 ramspeed while memtest stable, even at 3.33GHZ does not seem to like it when i play a videogame while priming so i lowered the divider and am running at 1000 ramspeed and that worked for an hour so i decided to start lowering the vCore live while playing the game and priming. got it all the way down to 1.2 vcore and 1.21 vtt

when i lowered vcore to 1.18125 (3 steps away), it failed so im sticking with 1.2 and testing that.

as you can see from earlier, i had the vcore up way higher(1.26875), but was unable to be stable past 3.2 with anything less than a 1.210VTT

which leads me to suspect that increasing the vtt some more might stablize a higher clockspeed.

anyone know what the the vtt qpi voltage affects? and a safe range? do i need additional cooling elsewhere? like a north or southbridge or something.

about to test at 21 x 167 multi and 20 x 175 for 3.5 ghz at the lower voltages and ramspeeds. and then increase the VTT abit.