i5-750 mild OC

I started with an i3-530 and found a really nice i5-750 deal and two weeks later, I started to overclock it to see what kind of numbers I'd hit. I am quite impressed!

Don't know if there's a general show and tell type section but here's a quick shot of some of the components:


Core i5-750 under a Scythe Mugen 2
G.Skill DDR3 1600 CL7D
Gigabyte P55A-UD3

CPU-Z validation:
http://valid.canardpc.com/show_oc.php?id=1263722

Temps are quite nice so far. With a room temp of 25C, case temp is usually 0.3C higher even though the motherboard sensor shows 30C. CPU temp (external) is 23C idle and 45C on load.

Core temps are below (Core 0, 1, 2, 3, min and max).

For LinX (default settings):
32 - 29 - 33 - 29
58 - 57 - 55 - 55

Prime95 (blend)
31 - 29 - 32 - 28
52 - 51 - 51 - 50

IntelBurnTest (Memory on 2047)
31 - 29 - 32 - 28
58 - 57 - 56 - 56

Full CPU load generates 185watts and 70 on idle so this is quite nice
I'm going to try to keep it at around this speed and work on lowering voltages.
Will post more results and configs later but with the World Cup, I find myself having less time OC'ing

Thanks for looking!

Mine does 3.8ghz at one tic above stock voltage, and 4ghz if I raise it a few notches

what is your voltage according to cpuz? the voltage there is always different than in BIOS and i cant figure it out

This has been running 100% load folding on all four cores for two days now. It's totally stable at 4ghz with a little more voltage, but our air conditioner is off and since this is my HTPC and it has a low profile air cooler, I backed it down to 3.8ghz at roughly stock voltage for now due to temps.

those idle temps are wrong... you are in a 25c room... but you have a 23c idle?

computerpro3 said:

This has been running 100% load folding on all four cores for two days now. It's totally stable at 4ghz with a little more voltage, but our air conditioner is off and since this is my HTPC and it has a low profile air cooler, I backed it down to 3.8ghz at roughly stock voltage for now due to temps.

Click to expand...

Nice, my i5 I have to slightly crank the voltage to get 3.8GHz and to get 4.0GHz I need to push the voltage much higher.

Also I notice at 4GHz things actually operate slower for some reason. I've run prime95 for a few hours without errors, and run number crunching software for hours which runs quicker at 4 than 3.8, but other tasks like opening and closing programs are noticably slower at 4 than 3.8. For that reason I backed it off to 3.8GHz, even though number crunching was faster at 4.

Mine runs 4ghz at 1.35v in bios, 1.296 in windows at load. I'm not really scared of the voltage though, as the most it sees after long gaming sessions are temps in the mid sixties.

Grats though.

Since you have 1600Mhz DDR3 memory, you'll get better memory performance by running BCLK at 200Mhz with a 2:8 memory divider, but you'll lose turbo mode.



3.6Ghz (200x18) 1.164v
http://valid.canardpc.com/show_oc.php?id=1263895

3.2Ghz (200x16) 1.035-1.047v if you want ultra-cool load temperatures (20c cooler than 3.6Ghz with the crappy stock cooler):
http://valid.canardpc.com/show_oc.php?id=1263976

I've also been easily able to take it to 4.0Ghz stable with more voltage, but since this is a budget computer I built for my 62 y/o mother, a mild overclock is all it really needs.

Cyberbeing said:

Since you have 1600Mhz DDR3 memory, you'll get better memory performance by running BCLK at 200Mhz with a 2:8 memory divider, but you'll lose turbo mode.

Click to expand...

Does turbo mode help much with gaming performance? In regular usage turbo mode doesn't do anything for number crunching, only for general opening and close programs does it actually maintain the turbo multiplier.

computerpro3 said:

This has been running 100% load folding on all four cores for two days now. It's totally stable at 4ghz with a little more voltage, but our air conditioner is off and since this is my HTPC and it has a low profile air cooler, I backed it down to 3.8ghz at roughly stock voltage for now due to temps.

http://img84.imageshack.us/img84/5296/voltage.png

Click to expand...

nice. I think you got a nice CPU.

EricFX1984 said:

those idle temps are wrong... you are in a 25c room... but you have a 23c idle?

Click to expand...

yea, i thought that too. i just figured the heatsink is actually colder than room temp.. or maybe speedfan is reporting it wrong?

Cyberbeing said:

Since you have 1600Mhz DDR3 memory, you'll get better memory performance by running BCLK at 200Mhz with a 2:8 memory divider, but you'll lose turbo mode.

http://img38.imageshack.us/img38/6493/cachememc.png

3.6Ghz (200x18) 1.164v
http://valid.canardpc.com/show_oc.php?id=1263895

3.2Ghz (200x16) 1.035-1.047v if you want ultra-cool load temperatures (20c cooler than 3.6Ghz with the crappy stock cooler):
http://valid.canardpc.com/show_oc.php?id=1263976

I've also been easily able to take it to 4.0Ghz stable with more voltage, but since this is a budget computer I built for my 62 y/o mother, a mild overclock is all it really needs.

Click to expand...

Thanks for the tip! I tried that by doing 200x18 as per your suggestion and I can't get the system to be linx/ibt stable.i went as high as 1.21v.

EDIT: forgot my RAM was on 1.5v. bumped it to XMP spec (1.6v) and systems stable now going to try to lower the cpu voltage next

what kind of CPU VTT are you guys running? I've been trying 170-200 base x 18, 19, 20 multipliers along with an array of CPU vcores but nothing works. I'd just like to get 200 base clock stable and use 18 or 19 multiplier. I've only gone as far as 1.90v for CPU VTT and no go. dont really want to go past 1.21v. so what are your CPU VTT and PCH and other voltages with your i5 750 OC's?

truflip said:

what kind of CPU VTT are you guys running? I've been trying 170-200 base x 18, 19, 20 multipliers along with an array of CPU vcores but nothing works. I'd just like to get 200 base clock stable and use 18 or 19 multiplier. I've only gone as far as 1.90v for CPU VTT and no go. dont really want to go past 1.21v. so what are your CPU VTT and PCH and other voltages with your i5 750 OC's?

Click to expand...

>>Advanced Frequency Settings
CPU Clock Ratio: 20x
QPI Clock Ratio: 32x
BCLK: 200
Extreme Memory Profile (X.M.P): Disabled
System Memory Multiplier (SPD): 8.0
PCI Express Frequency (MHz): 100
C.I.A. 2: Disabled
CPU Clock Drive: 700mV
PCI Express Clock Drive: 700mV
CPU Clock Skew: 0ps

>>Advanced Voltage Settings
Load Line Calibration: Disabled
CPU Vcore: 1.35000V
QPI/VTT Voltage: 1.150V
PCH Core: 1.050V
CPU PLL: 1.800V
DRAM Voltage: 1.560V
DRAM Termination: 0.750V
CH-A Data VREF: 0.750V
CH-B Data VREF: 0.750V
CH-A Address VREF: 0.750V
CH-B Address VREF: 0.750V

thanks psilence. i'll give that a try tonight. ive done 1.35v @ 3.8ghz and 1.21v VTT, 1.64v RAM to run at 1600mhz XMP, but my clock drives were at 800, 900mv. what roles do these two play in OC'ing? Also will try with LLC disabled (to follow intel spec). I always thought I was supposed to turn that off because it kept dropping and increasing the cpu vcore and i thought that was causing instability.

For VTT you want to be within 0.5v (or 0.45v to be extra safe) of your DRAM voltage.

If your DRAM voltage is 1.65v, your absolute minimum VTT is 1.150v. Using a VTT of 1.225v is a good starting point when overclocking. It your CPU OC and RAM is stable at 1.225v VTT then you can try lowering it, but I wouldn't go lower than 1.175v (because of slight voltage drops under load). If things aren't stable, you can raise your VTT as high as the 1.4v maximum if need be.

Stress testing with LinX seems to be a good way to see if your VTT voltage is too low, even if you otherwise seem to be stable with other stress testers. Pay close attention to your GFlops numbers between high and low VTT voltages. If your GFlops numbers ever drops off significantly (for example, ~20%) compared to higher VTT voltage, you really aren't stable at all, even if LinX doesn't produce any errors..

Thanks Cyberbeing. I didn't have 1.225 so i went ahead and used 1.25v. bumped up my ram to 8x multi so it runs at 1600mhz. set it all to default timing and voltage (1.65v but mb only has 1.64v). CPU vcore was at 1.3v in bios.

booted up fine. ran LinX fine cept something inside the computer makes some noise when CPU is 100% load (running linx). Heres a sound clip:

http://www.youtube.com/watch?v=dNwxI2LRnsY

Gflop numbers were around 52 and never +/- 20%

any idea what is causing this?

Sounds like classic cap whine to me. It's not much too worry about. My video card causes my psu to do the same thing in certain circumstances.

Anything to report back, truflip? Did all go well?..

yes and no. i got 200x18 to boot up with voltages higher than I've seen in this thread but at 100% load, something in the components would make what one guy calls a "cap whine"

I turned everything back to 170x20 for the time being and just basically enabled all power saving features along with lowering voltages and then tightening timings.

the cap whine kind of scared me lol

truflip said:

yes and no. i got 200x18 to boot up with voltages higher than I've seen in this thread but at 100% load, something in the components would make what one guy calls a "cap whine"

I turned everything back to 170x20 for the time being and just basically enabled all power saving features along with lowering voltages and then tightening timings.

the cap whine kind of scared me lol

Click to expand...

How high did you need the voltage to get that? I find my i5 runs up to 3.8GHz with minimal voltage increase, but to get above 3.9 I really had to bump up the voltage (I dont bother running it at 4GHz for daily computing, not worth the voltage and heat increase).

On my P55A-UD3 I did start to get funny motherboard noises at around 3.9GHz even though it was stable in prime95, but I bumped up the voltages a bit more and it got rid of the noises. Also I think I might have had one of the voltages set to "Auto" (I dont remember which one) and setting it manually helped.

For day to day computing I actually just clock it back down to stock speeds as games run fine and the computer is snappy enough for general tasks. When I have to do single thread number crunching (one program I use for work can't multi thread) I'll run it at 160 BCLK with turbo boost on, which ends up being 3.84GHz (x24) on a single thread and drops to 3.36GHz (x21) when it runs multiple cores, running turbo boost gives you a high clock for single thread number crunching without requiring a very high voltage. When I have to run simulations that actually use all 4 cores, I'll make a quick stop off in the bios and turn off turbo boost, change it to 200 BCLK, 19x multiplier and bump the voltage up a few notches.

The number crunching sims I run take several hours to solve, so it doesn't bother me having to stop off in the bios to change it before and after sims.

truflip said:

yes and no. i got 200x18 to boot up with voltages higher than I've seen in this thread but at 100% load, something in the components would make what one guy calls a "cap whine"

I turned everything back to 170x20 for the time being and just basically enabled all power saving features along with lowering voltages and then tightening timings.

the cap whine kind of scared me lol

Click to expand...

Google cap whine and you'll see that it has to do with frequency and not really how much power is drawn. Like in Oblivion it happens when I talk to someone and see a close up of their face even with vsync but it doesn't happen in Crysis. It's the a component in your psu that's seeing just the right frequency for the vibrations to be audible. I would avoid it if possible but it's not much of a cause for concern.