So I'm trying to OC my Q6600 and things go great with memtest. I can run it for days.
When I try Prime95 (the x64 version), I can run it for several hours but then suddenly the computer will blue screen for a second and instantly reboot. Prime95 doesn't show any errors, it just instantly reboots the entire system.

Have you ever heard of Prime95 acting this way?

that means your OC is not stable it FAILED simple!

try again.

if you any help other then why it Reboot itself then list your full spec and VID for your Q6600.

There are a few possibilities. It could be your motherboard FSB doesn't clock as high as you are trying to clock it. You might have inadequate voltages set. You could have bad memory......etc. What I would first try is to see if you memory is being funny using memtest86 and creating a bootable cd-rom and testing. Next I would say that you need to see what your MB FSB max is. I know gigabytes support 1600 mhz fsb by overclock. However, Abit won't support it on their IP35 PRO. You basically have to take your memory speed an multiply it by 4. However, first you have to half your memory speed then multi by 4. so for ddr2 800 you have to half it = 400 then multiply by 4 then you get 1600 mhz. The stock 333 clock speed of your processor x 4 = 1333 FSB. There are many things that could be creating the error.

I just thought that Prime95 would report an error on that core and then stop working that core. I didn't think it would reboot my entire computer.

Here's my system:
Cosmos 1000 Case
P5E WS PRO (BIOS V202)
Q6600 (G0)
Zalman 9700NT
XFX 8800GT
Corsair 8G 4x2G DDR2 800Mhz
Corsair HX750w
4x 500G Seagate HDD
XP Pro x64

Here's what she's running at currently:
Q6600 (GO) @ 3.01Ghz 333X9
1.2750v in BIOS CPU-Z shows 1.232v @ idle and 1.200v @ 100% load.
43-42-39-47 idle and 65-63-63-67 load

VID is 1.2875v

Memory is DD2 800Mhz running at 667Mhz 4-4-4-12 @2.1v

Ratio 1:1

So what do you think? By passing memtest for hours on end, I think my memory should be OK right? So what do you recommend for this processor? I'd like to keep the OC around 3.0Ghz.

When I think of it, I've had Prime95 quit a number of times, but it never caused the computer to blue screen and crash out, followed by an instant reboot. This sounds to me more like an overheat has occurred and the computer is resetting itself to prevent damage. Have you monitored the temperatures while running Prime95? Its something I always do, as I like to know how warm things are getting before things break down.

I always monitor the temps. Nothing looks out of place.
Here's a HWmonitor readout:


Voltage sensor 0 1.18 Volts [0x94] (CPU VCORE)
Voltage sensor 1 11.88 Volts [0xD5] (+12V)
Voltage sensor 2 3.30 Volts [0xCE] (AVCC)
Voltage sensor 3 3.30 Volts [0xCE] (+3.3V)
Voltage sensor 4 0.10 Volts [0xD] (VIN1)
Voltage sensor 5 5.06 Volts [0xD3] (+5V)
Voltage sensor 6 1.46 Volts [0xB6] (VIN3)
Temperature sensor 0 40°C (104°F) [0x28] (SYSTIN)
Temperature sensor 1 50°C (122°F) [0x64] (CPUTIN)
Temperature sensor 2 125°C (256°F) [0xF9] (AUXTIN)
Fan sensor 0 1140 RPM [0x25] (SYSFANIN)
Fan sensor 4 917 RPM [0x2E] (AUXFANIN1)

Intel Core 2 Quad Q6600 hardware monitor

Temperature sensor 0 61°C (141°F) [0x27] (core #0)
Temperature sensor 1 61°C (141°F) [0x27] (core #1)
Temperature sensor 2 60°C (140°F) [0x28] (core #2)
Temperature sensor 3 65°C (149°F) [0x23] (core #3)

GeForce 8800 GT hardware monitor

Temperature sensor 0 59°C (138°F) [0x3B] (GPU Core)

ST3250310NS hardware monitor

Temperature sensor 0 34°C (93°F) [0x22] (HDD)

I OCed my E2180 and yes if ur about right you get a red box and an error, but when i was off with voltages I got an instant reboot. Just raise voltages and watch temps. Also 2.75v .....I hope thats wrong lol.

Also do the temp Calibration stickied on the top of the section.....big help and knowledgeable. I was off by 5°C too low

Basically what iluv. just said below

My bad Silverion77 that should read 1.2750V

look at it like this
Red box says fail means you are close to success OC(minor tweaks needed)
reboot or BSOD means you are very far off from success OC(LOADS OF TWEAKS NEEDED)

Well we need the VID from the bios not from a program like cpu-z because those are inaccurate. I know that the proc is like 1.3250 stock VID. I usually give it a slight bump in voltage. You don't have a problem with FSB cause all board support that FSB and your does too. 1333 FSB. Processor is stock at 1066 FSB. Anyways, I say it is voltage problem if those temps are under prime95 load. I would say that you should get the new coretemp

www.alcpu.com

Tell me what the temps are under load. Like I said. I'll bet it is a voltage problem.

As Gahleon said, bump up the CPU voltage, probably a minimum of 1.35v, or possibly up to 1.4v. If you haven't done it already, you might try bumping the ram voltage up to as much as 2.1v.

Well, I check in the BIOS and I can't find any VID readings.
But again CoreTemp (Version .99) says the VID is 1.2875v.

I think the max voltage for a Q6600 (GO) is 1.5v.
Do you think it's safe to go higher?
Here are my temps and volts under 100% Prime95 load:
BIOS 1.275v Idle
CPU-Z 1.232v Idle
CPU-Z 1.200V Load

43-42-40-47 Load
65-63-63-67 Load
By the way my processor is lapped and I'm using a Zalman 9700NT.

It will run for about 2.5hrs like that until the whole system reboots.
I can run memtest forever and no errors.

Memory is at 2.1v.

Sorry those temps are:
43-42-40-47 Idle
65-63-63-67 Load

Memtest doesnt rly test CPU, just memory....so its the CPU voltages most likely.

Go up to 1.5v sure....just watch temps.