LGA775 Core2Duo, Core2Quad OVERCLOCKING guide

[harrynowl]

Hi, welcome to my guide for LGA775 overclocking!

 

I felt like writing this guide because LGA775 can still be a capable platform, plus overclocking is fun. I also see a fair amount of misinformation about LGA775 and overclocking (e.g. they aren't unlocked so can't be overclocked.) So I just felt like putting a guide out there for those interested in doing it, or for those who just want to learn a thing or two.

 

 

Let's start off with some basic terminology that you'll use when overclocking, some of this may be specific to LGA775.

 

CPU Voltage (Vcore): This is the voltage delivered to the CPU. Generally when overclocking you increase the voltage to gain clock speed headroom. Typical stock voltage for LGA775 CPUs is between 1.15v and 1.325v. Generally a lower stock voltage means for a better chip.

 

CPU FSB Voltage: When pushing for higher overclocks you may need to increase the FSB voltage. Most chipsets can handle around 1.3-1.4v max.

 

DRAM Voltage: This is the voltage to the DRAM, sometimes you'll have to increase this is overclocking pushes your motherboard out of the DRAM spec. However in most cases you can just set it to the set DDR2 standard for your memory kit (Generally between 1.8 and 2.1v).

 

NB Voltage: Voltage to the north bridge, may need to be increased when pushing for bigger overclocks. Generally safe up to around 1.4v

 

SB Voltage: Voltage to the south bridge, may need to be increased when pushing for bigger overclocks. Generally safe up to around 1.4v

 

CPU ratio: This is the clock ratio set by Intel. Typically ranging between 6 and 10 on most Intel CPUs. All but the extreme edition CPUs have what we call a "locked" ratio, which means it can't be changed. Because of this there's a big misconception that I see quite often on the forum that LGA775 CPUs can't be overclocked. The clock speed is calculated by ratio*bus speed/frequency. (e.g. 10 x 333 = 3330MHz)

 

Bus speed: The bus speed is 1/4th of the FSB speed. So common FSB speeds on LGA775 are 800, 1066 and 1333MHz. This means that each CPU would have a bus of 200, 266 and 333mhz respectively. When we increase our bus speed we are increasing the effective clock speed of a CPU, as we're increasing the amount the ratio is multiplied by. (e.g. 10*400=4000HMz). Bus speed also comes into RAM clocks, but we'll get to that later.

 

FSB speed: The front side bus is the bus that controls the memory communications between the cache, when overclocking the FSB speed is increased. A pre-defined FSB is given to each CPU, for example a Core2Quad Q6600 has a FSB of 1066 (leading to a 266mhz bus speed). The FSB requires memory at least twice the speed of the bus speed (1:4 from FSB). So a CPU with a 800MHz FSB can only operate at above DDR2 400MHz. And a CPU with an FSB speed of 1333 must have at least DDR2 667 MHz.

 

CPU Stepping: CPU stepping can be referred to the 'revision' of a CPU. Generally later steppings are capable of better things. For example on 65nm Q6600s the G0 stepping was a much better overclocker than the earlier B3 revision of the stepping. And on 45nm we had a similar with between C0 and E0 (E0 being better).

 

Motherboard Chipset: A bit like today where we have H81, B85, H97 and Z97 we had chipsets. Each chipset is aimed at a certain price points and this leads to some being better than others. Good LGA775 chipsets are as follows: 975X, P35, X38, 680i SLI**, P43, P45 and X48.

 

**680i SLI is known to struggle with Core2Quads due to some chipset errata.

 

 

 

 

Some basic maths:

 

I'll use 2 CPUs as an example. I'll choose two popular ones, the Q6600 Core2Quad and the E8400 Core2Duo.

 

Both CPUs had a CPU ratio of 9x. However one runs at 2.4GHz and one runs at 3GHz, why?

 

Well the E8400 has a higher FSB speed. (1066MHz vs 1333MHz). This means the bus speed for the two CPUs is different (remember, ratio * bus == clock speed). So the 2400MHz for the Q6600 is calculated with 9*266MHz and the 3000MHz for the E8400 is calculated by 9*333MHz.

 

Because of this the memory frequency will rise also, as the lowest memory speed is 1/2th the FSB or 2x the bus speed. So if we change our FSB to 1600MHz the memory (if previously running at DDR2 667) will now clock up to 800MHz. We can combat this by either raising the voltage and loosening the timings, or by changing the divider, this means we choose say, DDR2 533MHz but as the bus speed is higher the effective frequency will be higher. This can lead to some strange frequencies. If you're using a nvidia chipset like 680i or 790i you can keep memory speed unlinked to the CPU bus speed. This is helpful as it means you can generally keep a very consistent memory speed.

 

 

Motherboard chipsets and how they compare:

 

I'm just going to list the bus speeds most chipsets can reach at a push, from lowest to highest.

 

Intel:

975X: 400MHz

 

P35: 500MHz

X38: 500MHz

 

X48: 600MHz

P45: 625MHz (generally extreme OC)

 

nVidia:

650i: 450MHz

680i: 500MHz (excluding core2quads, which struggle with 333mhz)

 

750i: 450MHz

780i: 475MHz

790i: 500MHz

 

 

So now to the actual overclocking, you'll need to target a desired clock speed. I'll list some common Intel CPUs and some average overclocks.

 

E5200 (2.5GHz stock): 3.7GHz average OC.

E6600 (2.4GHz stock): 3.5GHz average OC.

E8400 (3GHz stock): 4GHz average OC.

Q6600 (2.4GHz stock): 3.5GHz average OC.

Q9300 (2.5GHz stock): 3.4GHz average OC.

Q9550 (2.8GHz stock): 4GHz average OC.

Q9650 (3GHz stock): 4.1GHz average OC.

 

So, identify the base speed and ratio for your CPU. A good tool to do this is CPU-Z, or you can just use your BIOS. 

Now set a target clock speed for your processor. A fairly achievable clock on almost any CPU (except a lot of the lower clocked 800mhz fsb cpus like pentiums/celerons, I'd target 2.8) would be 3.3GHz.

 

So head into your BIOS, familiarize yourself with the settings and find the ones I've mentioned in the rest of this guide.

Now when you find FSB speed or Bus speed (I find AMI BIOS list bus, and Phoenix FSB). And set it to what you've calculated for your CPU. (frequency = bus*ratio). Now also add 50mV to your CPU (0.050v). 

Reboot into Windows, run some benchmarks/stress tests and see if it's stable. If you're happy and want to push more, you can do the calculations to achieve higher clock speeds. If you're running into instability, try increasing voltage for some of the things I've mentioned above. You should also make sure your RAM is not running miles higher than it should be.  When aiming for high clocks it's generally beneficial to get faster RAM. If you're running DDR2-667 and are chasing a 500MHz+ FSB, you'll find you're running about 250MHz out of spec at minimum. This is because of the FSB:DRAM ratios possible with the chipset. Again nVidia chipsets are generally more flexible with unlinked ratios.

 

1:1 FSB:DRAM ratio: When overclocking on this platform a lot of people aim to get a 1:1 FSB/DRAM ratio, this means that the CPU doesn't have to "wait" on the RAM when communicating to the bus. This results in extra performance but isn't always achievable and isn't a massive gap either. This generally works best with low timings for speedy CPU/DRAM data exchange. To achieve this you'd set a DRAM ratio equal to your FSB. So if you had a FSB of 500, you'd choose DDR2-1000MHz (500MHz effective).

 

 

Recommended voltages:

65nm Dual core: 1.5v

65nm Quad core: 1.425v

45nm Dual core: 1.4v

45nm Quad core: 1.35v

 

Thanks for giving this a read

 

Feel free to post your results and some benchmarks!

http://valid.canardpc.com/kj3mw1

http://hwbot.org/submission/2649485_harrynowl_cinebench_r11.5_xeon_x5450_5.25_points?recalculate=true

[bry.yyyy]

guess need to find new LGA 775 Mobo cause i have Pentium Dual Core 2.6 Ghz Not doing anything

[harrynowl]

guess need to find new LGA 775 Mobo cause i have Pentium Dual Core 2.6 Ghz Not doing anything

well. at 4.65ghz I beat an FX8350 @ 5.35ghz in cinebench 11.5 + r15 (single threaded), so lga775 is still worth something

[bry.yyyy]

well. at 4.65ghz I beat an FX8350 @ 5.35ghz in cinebench 11.5 + r15 (single threaded), so lga775 is still worth something

lol you beat the hell of FX 8350

[qwertywarrior]

overclocking back in the day was not for the weak of heart

[harrynowl]

overclocking back in the day was not for the weak of heart

I love LGA775. That's where I learned a lot about computers. I had some OEM G31 board (Foxconn G31MX-K) and got my Pentium E2200 from 2.2GHz to 3.1GHz and I felt like some kind of god

 

(I was like 12).

[SkilledRebuilds]

Everyone should read up on BSEL Cpu mods too

Hardcore overclocking for dell / locked motherboards.

Essentially taking 1066mhz fsb to 1333mhz which upped the core mhz.

You had to remove Cpu... and tape over certain pins.

[Faa]

Any reason you listed max safe voltage for C2Q 45nm 1.35V? Max safe voltage is 1.45V.. By the way, especially for this platform, I would first do small fft's in prime95 just to rule out the memory/and whatever again goes along with it and quickly getting an idea if the vcore was enough. Once that's stable, run blend and tweak the VTT/Dram voltage perhaps/NB. There are a few more voltages though like CPU GTL, DRAM GTL, Northbridge as well, on gigabyte boards its called reference, CPU GTL should be 0.67 of your VTT. Gigabyte boards were scaling this automatically like it should be set.

Include the 1:1 cheat and explain why faster RAM can be needed to achieve higher clocks, you explained this already with the FSB. FSB is quad pumped by the way, so a FSB of 333MHz is 1333MHz (can be seen in GPU-z fsb vs rated fsb).

1.40-1.45V for the FSB/NB/SB is quite a lot. I needed like 1.2-1.3V for the NB/SB for 447MHz/900MHz

[harrynowl]

Everyone should read up on BSEL Cpu mods too

Hardcore overclocking for dell / locked motherboards.

Essentially taking 1066mhz fsb to 1333mhz which upped the core mhz.

You had to remove Cpu... and tape over certain pins.

I'm fortunate enough to not need to do that. But I could add some references in my guide.

 

I could also do PLL

[harrynowl]

Any reason you listed max safe voltage for C2Q 45nm 1.35V? Max safe voltage is 1.45V.. By the way, especially for this platform, I would first do small fft's in prime95 just to rule out the memory/and whatever again goes along with it and quickly getting an idea if the vcore was enough. Once that's stable, run blend and tweak the VTT/Dram voltage perhaps/NB. There are a few more voltages though like CPU GTL, DRAM GTL, Northbridge as well, on gigabyte boards its called reference, CPU GTL should be 0.67 of your VTT. Gigabyte boards were scaling this automatically like it should be set.

Include the 1:1 cheat and explain why faster RAM can be needed to achieve higher clocks, you explained this already with the FSB. FSB is quad pumped by the way, so a FSB of 333MHz is 1333MHz (can be seen in GPU-z fsb vs rated fsb).

1.40-1.45V for the FSB/NB/SB is quite a lot. I needed like 1.2-1.3V for the NB/SB for 447MHz/900MHz

I'm working on it, I think I mentioned that the FSB/bus was 1:4, but the DRAM min speed is 1/2 the FSB.

 

I said max recommended voltages, ideal for 24/7 use. From my experience the quads can get pretty toasty pretty quick

[qwertywarrior]

I love LGA775. That's where I learned a lot about computers. I had some OEM G31 board (Foxconn G31MX-K) and got my Pentium E2200 from 2.2GHz to 3.1GHz and I felt like some kind of god

 

(I was like 12).

ohh man same here

i oced soo many 775 socket cpus

e7200 QX6700

a QX6800 with a triple rad  for cooling

a Q6600 G0 stepping to 3.2ghz  on a stock cooler

 

 

here is a E7200 on a G31 i OCed

 

i loved Computers a lot during the 775 gen socket !

after that it was meh  because a lack of competition and everything was just moving slowly

[SeanAngelo]

i wanna overclock my Q8300 but idk if it can

[harrynowl]

i wanna overclock my Q8300 but idk if it can

Well, give the guide a read, you'll find it can

 

you can probably get 3.3 from that, motherboard willing.

[harrynowl]

lol you beat the hell of FX 8350

poor amd

[Faa]

I'm working on it, I think I mentioned that the FSB/bus was 1:4, but the DRAM min speed is 1/2 the FSB.

 

I said max recommended voltages, ideal for 24/7 use. From my experience the quads can get pretty toasty pretty quick

Trying to remember, at 333MHz in a 1:1 ratio RAM would end up to be 667MHz so your requirement that RAM has to be twice at the FSB speed is correct (333*2=667mhz) or just half at the rated FSB on CPU-z (667/1333mhz = 1/2). "Bus speed is 1/4th of the FSB", I assume you meant the bus speed in the bios is 1/4th of the speed thats quad pumped. Tbh leave this out, honestly you're not a lot with this quad pump theory, as long as you know that your ram speed should be twice as fast as the FSB speed in the bios that should do it.

- If I OC the FSB by 67MHz (from 333MHz);

400MHz FSB with 800MHz RAM would be 1:1 a FSB:DRAM ratio

- If I decide to get rid of my DDR2 800MHz stick and get a 1600MHz DDR3 stick and lets say my CPU can do it easily;

400MHz FSB with 1600MHz RAM would be in a 1:2 FSB:DRAM ratio.

Side note: It was advised to lock the PCIe bus to 100.00MHz and the PCI/ to 33MHz or 33.33MHz can't remember it exactly anymore  

My experience with core2's is quite different they weren't running hot at all under a NH-D14. I can remember my Q9550 at 3.8GHz with 1.36V, idle 53° and full load after hours apparently 55°. I couldn't do 4GHz at all, so I just went extreme nuts and bumped every voltage out there except SB/GTL's, at 1.45Vcore wasn't even breaking 65° and still not stable A friends E7600 I think it was, had a stock clock of 3.06GHz and a multiplier of 11 afaik, got that thing in less than a minute at 3.8GHz. A higher multiplier was awesome, lower FSB clock which has a lot more headroom with slow ram was just epic. He had a NH-D14 as well, wasn't even breaking 45°.. Heres a video of a guy that shows his temps at 4GHz with a Q9550 & nh-d14; youtube.com/watch?v=le5VCSL6trk

Sandy bridge was a different story for me, 4.7GHz and 1.37V gave me like 80° so I just upgraded my nh-d14 to a H100. Found my Q9550 at 3.8GHz using less power than my 2600K, but isn't a surprise when SB pulls a GHz higher clock

Btw nice OC, just seen it, that's just a 2500K

[bry.yyyy]

well finding LGA 775 Mobo in here is actually hard

my old 775 Mobo is ASUS P5KPL-AM SE And i fucked up

so that mobo is broken

[bry.yyyy]

and for note i don't know that cpu still work or not i already touch that gold (i don't know the name of it )

[bry.yyyy]

anyone know what best socket for LGA 775 ?

[SeanAngelo]

Well, give the guide a read, you'll find it can

 

you can probably get 3.3 from that, motherboard willing.

i'm scared that my cpu cooler wouldn't be able to handle the heat at that kind of speed, i know nothing about overclocking but i'm willing to try hehe.

 

my motherboard is an ASUS P5G41C-M LX

[harrynowl]

Trying to remember, at 333MHz in a 1:1 ratio RAM would end up to be 667MHz so your requirement that RAM has to be twice at the FSB speed is correct (333*2=667mhz) or just half at the rated FSB on CPU-z (667/1333mhz = 1/2). "Bus speed is 1/4th of the FSB", I assume you meant the bus speed in the bios is 1/4th of the speed thats quad pumped. Tbh leave this out, honestly you're not a lot with this quad pump theory, as long as you know that your ram speed should be twice as fast as the FSB speed in the bios that should do it.

- If I OC the FSB by 67MHz (from 333MHz);

400MHz FSB with 800MHz RAM would be 1:1 a FSB:DRAM ratio

- If I decide to get rid of my DDR2 800MHz stick and get a 1600MHz DDR3 stick and lets say my CPU can do it easily;

400MHz FSB with 1600MHz RAM would be in a 1:2 FSB:DRAM ratio.

Side note: It was advised to lock the PCIe bus to 100.00MHz and the PCI/ to 33MHz or 33.33MHz can't remember it exactly anymore  

My experience with core2's is quite different they weren't running hot at all under a NH-D14. I can remember my Q9550 at 3.8GHz with 1.36V, idle 53° and full load after hours apparently 55°. I couldn't do 4GHz at all, so I just went extreme nuts and bumped every voltage out there except SB/GTL's, at 1.45Vcore wasn't even breaking 65° and still not stable A friends E7600 I think it was, had a stock clock of 3.06GHz and a multiplier of 11 afaik, got that thing in less than a minute at 3.8GHz. A higher multiplier was awesome, lower FSB clock which has a lot more headroom with slow ram was just epic. He had a NH-D14 as well, wasn't even breaking 45°.. Heres a video of a guy that shows his temps at 4GHz with a Q9550 & nh-d14; youtube.com/watch?v=le5VCSL6trk

Sandy bridge was a different story for me, 4.7GHz and 1.37V gave me like 80° so I just upgraded my nh-d14 to a H100. Found my Q9550 at 3.8GHz using less power than my 2600K, but isn't a surprise when SB pulls a GHz higher clock

Btw nice OC, just seen it, that's just a 2500K

I added some stuff about fsb:dram ratios in post. Yea high multi chips were good, but I got my X5450 for £23

[harrynowl]

anyone know what best socket for LGA 775 ?

LGA775 is the best LGA775 socket.

 

If you mean motherboard, I find you can't go wrong with the ASUS P5Q or the Gigabyte EP45-UD3P. Both are generally ~£50. I've borrowed a P5Q right now and it's fantastic. In order of preference nForce 680i -> P35 -> 790i -> P45

 

i'm scared that my cpu cooler wouldn't be able to handle the heat at that kind of speed, i know nothing about overclocking but i'm willing to try hehe.

 

my motherboard is an ASUS P5G41C-M LX

What cooler? You can usually get some overclock without adding volts. Looks like a G41 board. see if you have any options in your bios.

[SeanAngelo]

What cooler? You can usually get some overclock without adding volts. Looks like a G41 board. see if you have any options in your bios.

Arctic cooling freezer 7 pro rev 2 LOL

 

alright, ill try to look in the bios now

[harrynowl]

Arctic cooling freezer 7 pro rev 2 LOL

 

alright, ill try to look in the bios now

Eh, it'll manage a bit.

[bry.yyyy]

LGA775 is the best LGA775 socket.

 

If you mean motherboard, I find you can't go wrong with the ASUS P5Q or the Gigabyte EP45-UD3P. Both are generally ~£50. I've borrowed a P5Q right now and it's fantastic. In order of preference nForce 680i -> P35 -> 790i -> P45

 

What cooler? You can usually get some overclock without adding volts. Looks like a G41 board. see if you have any options in your bios.

I Mean chipset LOL Screw me cause i wrote wrong

i only found G31 And G41M

Which one should i pick ?

[harrynowl]

I Mean chipset LOL Screw me cause i wrote wrong

i only found G31 And G41M

Which one should i pick ?

g41 is better... but I'd save up