Overclocking i5 750

AncientW

Hi guys.
I'm thinking of overclocking my i5 750 Lynnfield processor. The default clock speed is 2.67Ghz, I overclocked it to 3.2Ghz without increasing Vcore voltage and it's stable. By how much should I increase the voltages to get it to 3.6Ghz? I don't want to burn my CPU, I don't have money for a new one.

EDIT: I forgot to mention i have a Gigabyte P55M-UD2 motherboard.

Monotype

Increase it in small steps like 0.1GHz at a time until you reach 3.6. A quick stability test each time like hyperpi is handy to see that you're still somewhat stable.

Then test for stability. If it's not stable, slowly increase the voltage - only in one or two small steps at a time. Every time you're running stability test, keep your eye on the temperatures. If the temps get too high, you need to reduce the overclock.

AncientW

Hi.
Should I use 20x multiplier? I've read somewhere that for e.g. 20x160 (3.2Ghz) is slower than 10x320, or is this false?

EDIT: OK so I can go up to 3.3Ghz with stock voltages, but there was a big loop. I could choose 1.25V (stock) and the next number was 1.31V I think 1.31V should be enough for 3.6Ghz or even more.
And what else do I have to increase? I only increased the Vcore voltages and BCLK.

Monotype

Yeah, 10x320 would be faster as you're overclocking the bus speed - however this also means that you're overclocking the RAM. You're probably best with sticking with the multipler of 20 for now and you can tweak it later if you prefer.

You should keep an eye on your RAM speed. Every time you increase the BCLK, you increase the RAM frequency also. If you have a RAM multiplier or divider, adjust it to keep below the recommended speeds labelled on the RAM when you bought it. When you are satisfied with the CPU overclock, you can overclock the RAM. You don't want to do both at the same time as you won't know what is causing instabilities.

AncientW

I brought the PC normally - I didn't build it and it doesn't say anywhere what RAM I have. All i know is that it's 4GB DDR3 and I think stock frequency is 1333MHz. BTW when i increase the BCLK, the memory automatically increased as well.

At 3.4Ghz with 1.31V my PC shut down itself and also got a BSOD, don't know what to increase/decrease :V I'm stuck at 3.2Ghz with stock voltages (1.25).

Monotype

Alright, so if you have 1333MHz RAM, change the RAM multiplier so that you're below that when you're overclocking. You can find more about your RAM by running CPU-Z @ cpuid.com.

How stable was 3.3GHz? Did you run prime95 or something to test it?
ftp://mersenne.org/gimps/p95v277.win64.zip

First thing to check is to make sure your RAM isn't going above 1333MHz (may come up as 667MHz) when you move to 3.4GHz. If you think that you need more voltage on the CPU, you should be OK going up to 1.35V, but keep a close eye on your temperatures.

AncientW

Not sure how stable 3.3 was. I think the max stable clock speed is 3.2. When i set my vcore to 1.31V and clock speed to 3.4 I got a BSOD when it restarted itself and i got a message saying something about the voltages and overclocking. My PC set all values back to default, so I don't know how I'm going to overclock it to 3.6 if it resets itself at 3.4..... -__-

Don't worry about temps, I'm after getting a Noctua 12mm heatsink, it's massive - barely fits in my tower my idle temps at 3.2 are 25-32C and at full load they reach 45-50C.

What do I have to change in order to keep my RAM at 1333MHz?

EDIT: This is what it says in CPU-Z
NB Frequency: 256.0 MHz

Timings:
DRAM Frequency: 800.0 MHz
FSB DRAM: 2:10
9-9-9-24
Command Rate: 2T

Also in SPD it says
Max bandwith: PC3-10700H (667 MHz)
Module size: 2048 MBytes

Monotype

There should be a multiplier under the RAM settings that it multiplies by the BCLK to get the RAM speed. Have a look around. If you can't find it, I'll have a read through the manual tomorrow to see if I spot it.

The memory tab is the actual speed it's running at. The SPD tab is information on the modules or what speeds they could run at.

So you've got PC3-10700 (Normally PC3-10666 or 667MHz or 1333MHz).
It looks like your RAM is overclocked at the moment - from 667MHz to 800MHz. Most modules are able to do this easily enough, but you need to higher timings to increase speed. You can mess around with these later when you have the CPU under control. The FSB:DRAM ratio is the one that you need to change, but it could be called a lot of different things in the BIOS like divider or multiplier.

AncientW

OK I went to BIOS and this is what I found out. The Memory Frequency is 1333 but right beside it it says 1600 so i think it's 1600MHz at the moment.

This is what it says in BIOS:
Memory Frequency(MHz) 1333 1600
System Memory Multiplier(SPD) [Auto]
PCI Express Frequency(MHz) [Auto]
QPI Link Ratio [Auto]
QPI Link Speed 5.76Ghz
Uncore Clock Ratio 16x
Uncore Frequency 2560MHz
DRAM Timing Selectable (SPD) [Auto]

Monotype

System Memory Multiplier is probably the one you're looking for. Take it off auto and put it at some value so your RAM speed stays below 1333MHz when overclocking.
It might be no harm to set the PCI-Express frequency to 100MHz so it doesn't get overclocked.

AncientW

OK, I'm going to do it right now till i see you online =D

AncientW

I set the PCI Express Frequency to 100MHz as you said. The System Memory Multiplier has these options: 6.0, 8.0 and 10.0. At 6.0 = 960, at 8.0 it says 1280 and at 10.0 it's 1600. so should I set it to 8.0 - right?

Monotype

Sounds right. Unless overclocking brings it beyond that. A small bit over 1333 should be okay anyway and shouldn't cause instability.

AncientW

OK I managed to get a stable system with the following setup.
Vcore: 1.25V
20x165 (3.3Ghz)
System Memory Multiplier: 8.0
Memory Frequency (stock 1333MHz) now 1280MHz
QPI Link Ratio: 32x
PCI Express Frequency: 100MHz
EIST: Disabled
C1 State: Disabled
LLC: Auto (don't know if I should enable or disable it)

But if i try going 3.4Ghz my PC wont boot and it will automatically reset all settings back to default. Also if I try setting Vcore from 1.25V to 1.31V then I still get a message saying that my PC has to reset all settings back to default, any ideas?

EDIT: Oh yea! It works. I tried setting Vcore to Auto then i went back to the voltages and the gap opened. e.g. before I could only pick 1.25V or 1.31V but now all voltages unlocked between 1.25 and 1.31
So I reached 3.7Ghz (didn't try more cause i reached my goal)
memory multiplier: x8.0
vcore: 1.275V
20x185
QPI link ratio: 32x
eist, c1 state: disabled
LLC: Auto
pci express: 100MHz

temps: idle: 35-40C full load (in prime95) 60 - 70C

AncientW

BTW my PC overclocked my RAM. I've set the Memory Multiplier to 8.0x but it changed from 9-9-9-24 to 10-10-10-27. Should I change them back to default setting? Or is this OK?

Monotype

Not really sure why more voltage options suddenly appeared but sounds like all is well now.
10-10-10-27 is slower than 9-9-9-24. Ideally you want low timings and high speeds. To test RAM, best one to use is memtest.org. You need to burn it to disc or blank USB and boot from it.

Make sure you run a long stability test on the CPU. At least 6 hours of prime95.

AncientW

why is it needed to leave my pc on full load so long? even if i play some game on ultra settings, my temps will be maybe 50 - 55C and i will never reach full load. also, i never play a game for longer than 2hours.

Monotype

It's more than just temperature testing. You're seeing that it is stable so that your data doesn't get corrupted or you don't get sudden shutdowns when you least want it.