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Overclocking my old boy ( Core 2 Quad q9400)

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Jan 11, 2017
So,i recently started upgrading my PC.I replaced everything,except the mb,cpu and ram,which will be replaced soon too.Currently I have Core 2 Quad Q9400 running on Asus p5q-pro with 4x2gb ddr2 a-data 800mhz ram running on dual-channel.i have managed to overclock the cpu up to 3.60ghz (from 2.66).It is definitely showing it's age,but overclocked it is still capable.So i need someone who knows how to clock this quads to help me.I have some basic knowledge,i have overclocked e7600 and q6600,but still i am not sure how to get the maximum out of this cpu until i get a new one,and i don't really understand the voltages :( .My FSB is 450 mhz and my ratio 8,making stable 3.6 ghz with maximum temps 65°(All my fans are on silent mode).I have set the voltage to 1.25 and it is stable (ran prime 95)..i tried to push the CPU up to 3.8ghz,and increasing the voltage,but the system is unstable,crashing and prime 95 crashing on first 5 minutes.So my question is what is the right voltage that i should set , and how much can i overclock this cpu to get the maximum out of it until i get a new i5. :-/
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main.png memory.png spd.png
Currently i have 1:1 DRAM : FSB (450mhz). Is my ram that bad,and is that my limiting factor?
What you should notice from that screenshot is your memory is overclocked. This may be you limiting factor. My suggestion is to add a bit of voltage to the ram (.05V) and if that doesn't work, loosen the timings to 6-6-6-XX...

Add8ng Vtt voltage should help as well. Do one thing at a time.
Ok,i increased the DRAM voltage to 1.84,and i changed the CPU fan to standart(from silent)to keep the temps lower,and it actually looks stable.(atleast it didn't crash on prime the first 5 minutes)Actually this might be the solution.Thank you for your fast response, i will keep you in touch and i want to ask a few questions:
for how long do you think i should run prime 95?
Should i be worried about ram overheating?
And do you think i will be able to hit 4Ghz.

I probably should have said that i have seasonic 750w 80+ bronze,it should be more than enough.Also i have 2x180mm and 1x120mm fans to keep everything cool.
I didn't think somebody will reply that fast,since core 2 quad is old tech.I just made my registration here today and i am already in love with this forum :)
Generally, we advise running Prime95 for at least two hours to confirm stability. You will see a temp spike at about 20 minutes and then again at about one hour so watch temps. Not sure what the TJMax is for that generation of Intel's but maybe 95c would be a good ballpark figure.

Yeah, when you overclock withe th FSB like you are doing the memory frequency rises along with it. The two are tied together. What is your memory divider set to now? Often, the memory divider has to be changed to compensate for this. So if the memory was rated for DDR2 800 then you would set the divider to DDR2 666 if you can't get the memory stable otherwise.

Does that CPU have an unlocked multiplier?
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Yes,i thought 2 hours, max 4 is enough in prime 95,but i asked because some people run it 12+hours.My TJMax is 100c and my Tcase is 71c.Yeah i started raising the FSB,because that way i get 1:1 fsb:dram ratio (people say it is better that way) and since i have old ddr2 ram,which is slow,i thought i might see benefit from overclocking it.Yes my memory is rated for ddr2 800. I just made tests.first i made the dram voltage 1.84,then i increased it to 1.86 and now i increased the timings to 6-6-6 (with stock voltage) and all of the tests failed :( Currently my memory frequency in bios is 951mhz.
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@ trents - The q9400 is not unlocked. FSB clocking is required. Unlocked chips of that generation had an "x" in the name. ;)

If your memory can barely make it to 450, it's not making it to 666. Your memory is spec'D to 400 mhz/ddr 800 amd you are at 900.

As far as stress testing everyone on here has a different opinion. I'd say 4 hours minimum for small fft and blend are typically sufficient.

I wouldn't worry about Tcase temps, and keep the cpu below 75C or so when testing as much above that causes instability.
It's DDR2 800 (PC2 6400) RAM isn't it? What I meant was starting the divider at the DDR2 666 level (333 in CPU-z) to make headroom.
I don't find any options,that can change the divider.Where should i search?

Hard to say. Maybe "Memory Frequency"? Keep in mind that what shows in the Memory Frequency line will reflect your overclock of the memory, not stock dividers.

- - - Updated - - -

It may be counterproductive to sacrifice memory frequency for a small increase in CPU overclock frequency since the quad cores in that generation of Intel CPUs tended to be starved for memory bandwidth anyway.
It's DDR2 800 (PC2 6400) RAM isn't it? What I meant was starting the divider at the DDR2 666 level (333 in CPU-z) to make headroom.
IIRC, he's already at the lowest divider 1:1 with fsb...666 =1333 while 400 = 800 mhz. It's a higher divider and would raise the memory speeds

It may be counterproductive to sacrifice memory frequency for a small increase in CPU overclock frequency since the quad cores in that generation of Intel CPUs tended to be starved for memory bandwidth anyway.
It was??? First time I recall hearing that!
Interesting. Not sure that supports what was mentioned though. I'd love to have seen benchmarks.
Okay,guys i tried alot of settings,but i can't manage to OC my CPU higher than 3,6Ghz.Obviosly something is limiting me,but i really don't know what.I may stay that way until i get a new CPU,because i am really amazed how this old cpu performs.
Remind us... did you try loosening the timings a bit as well as addING vram voltage?

You either hit your FSB limit on the board or that ram is holding you back. I'd raise it to 1.85V, loosen all timings by one, lower cpu multiplier, and see if you can push that fsb.
yes,i tried making the ram voltage to 1.86(since it adds 2 per click)(default is auto),and loosening the timings to 6.That did not work.I will trying lowering the multiplier ,to see if 450mhz is my board limit,but i hope not,because alot of people say the p45 chipset on this mb is very capable and people say they go up to 500.Even one site said,that the limit for this chipset is 625 fsb(i don't really know if that is true).
Every motherboard is different. The P5Q-Pro should be good for 450+ though I would imagine.

What about the heatsinks around the CPU? Below it? Are they getting hot to the touch? You may need to raise some voltage for FSB. Offhand I don't remember what it was called... Vtt??? Check the guide to see.
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Ok,so what i did here : i raised the fsb up to 500mhz and made the multiplier 7 and the ram set to auto(because i was not sure about setting it to 1002mhz).My pc booted and almost immediately restarted,then it froze on the windows logo.I gave it one more try by pressing the restart button and windows automatic repair showed and then wild bsod appeared.I changed the fsb back to 450mhz with 8x multiplier and the ram set to 901mhz and everything started as it should.Does that mean i don't get enough voltage for the fsb when going over 450?All voltage options are set on auto right now,except the cpu voltage which is set to 1.225,not to 1.25 like i said before.about the heatsinks,i will check them tomorrow,but hardware monitor shows maximum 35c for the motherboard(is this the chipset?).
bios_1.png bios_2.png bios_3.png
These are photos from my bios with my stable OC.One more thing that i tried to make the 3.8ghz oc stable is setting the fsb termination voltage to 1.30 and the test on prime 95 failed again.