p45 (asus p5q pro) / e8400 E0 voltages for 400 FSB?

[OCChronic]

I'm running an E8400, CO stepping, @ 475 x 8(3800 MHz) & 1.344v Vcore on an X38-DQ6 and I found that running the FSB overvolted by 0.25v and leaving the MCH voltage @ 'normal' in the BIOS runs best and is 24Hr rock-solid stable no matter what I throw at it, including multi-tasking during dual Prime95 blended test. If I leave the FSB at 'Normal', it fails most stability tests almost right away.

Orthos, Prime95 dual blended tests are excelllent for CPU stability testing while games like UT2004, UT3, and Crysis are excellent for overall system stability and will bring out any stability issues, especially in chipset and memory timings/voltages which Prime95 or Orthos may not reveal.

Many OC'ers out there sometimes runs their CPU's or MCH voltages too high and get mixed results during different stability tests when the CPU's FSB voltage is the one that needs to be raised.

If you are running a newer chipset capable of '1600+ FSB' then the MCH can run @ 400 FSB with no additional voltage. If you are running an E8400 then it's very likely that it can do at least 3.6 GHz @ normal vCore voltage.

The instability arises when you raise the FSB to 400 or higher and don't add any voltage to the CPU's FSB at all.

 

[walk2k]

Ok, just got another error in Orthos (in addition to a couple of mild crashes in 1 game) so I upped my vcore +1 keypress in the bios (from 1.225 to 1.23x?) measures = 1.208 (was 1.200) idle and 1.224 (was 1.216) under load. So far no errors or crashes even running Orthos in both Blend and CPU AND running 3dmark06 at the same time.

Temps tipped 65C (max ... VERY max). More like 55C in most games.

ALSO I hooked up my P3 Kill-a-watt to look at real power draw. This is a small power-brick type box that plugs into the wall socket, then you plug in the device you want to measure into its socket. It measures REAL power draw directly from the circuit..

This is all at 3.6Ghz. GPU is 8800GT 512 (G92) "superclocked" 650Mhz with a custom fan profile (duty cycle = 29% idle, 60-70% load).

Power ON = 150 watts

Idle in XP = 120 watts

Mild disk activity in XP = 130-150 watts

CPU stress test = 180 watts

3dmark06 GPU test (the fairys thing, always maxes the GPU temp and fan) = 209 watts.

Other games tested = around 200 watts.

3dmark06 -AND- Orthos (small/CPU) test running = 234 watts max recorded.

I also turned on Asus QFan on the CPU fan, with "turbo" profile. It brought idle CPU fan down to 900rpm (from 1700), temps stayed exactly the same at 41C then under full load it reaches 1900-2100rpm (about the same as no Qfan). So it's quieter at idle and provides the same or better cooling under load. Freakin awesome.

Glad I didn't go overboard on the power supply heh... I bought the case -and- 430W psu for like $120...

 

[darthjoe]

Ok, after getting 3.6 stable on my machine, I tried for my goal of 4.0ghz.

E8400 E0 Stepping
Asus P5Q Pro
ATI 4850
4GB Corsair XMS2 ddr2-800 ram
Antec Twelve Hundred Case
Arctic Freezer Pro 7 heat sink

I'm currently running stable at 4.0ghz (9x445), with Vcore set at 1.2650V, and ram at 1.9V. All other voltages set to auto. EIST has been left active.

Ambient temps: 77F

Idle temp: 33C
Load Temp (Prime95) 52C
Load Temp (IntelBurnTest) 61C

Computer booted at 1.2500V, but crashed during IntelBurnTest.
Computer booted at 1.2575V, but crashed during 1920x1200 game playing
Computer currently stable at 1.2650 with Prime95 and WOW running at 1920x1200 concurrently.

No plans to try and push this past 4.0, although it looks like I have some room. Haven't even hit 1.3V on Vcore yet. Very pleased with the upgrade over my E4300 I had overclocked to 3.0ghz.

 

[bludragon]

Nice results guys, thanks for sharing.

 

[walk2k]

More power draw tests...

"Shut down" (system off) = 1 watt.

"Standby" (in XP) = 2 watts.

Pretty good, my last PC (A64 X2, Asus A8N) was around 9-10 watts in standby.

 

[sheemone00]

After reading this thread and people saying that 400 should be a breeze on stock settings I went home and tried it, but alas its not stable.

I have a Corsair Twin2x4096 and currently have the Vcore set to 1.225 and the vDimm to 1.9 in the bios.

Is upping the vCore the only option or is there something else that needs to be adjusted?

Prime fails within 5 sec when FSB is 400 and fails within 50 min when FSB is 395.

I had the FSB set to 368 before reading the thread and that seemed stable @ stock settings.

EDIT: Interesting article I found: TUCH ME

 

[bludragon]

Well the reason I started this thread is that changing vcore alone did not seem to help my setup. Actually, I'm not stable at 400 MHz fsb and default volts even if I set the cpu multiplier down to 7.5 so that the cpu itself is not overclocked. As it is, I've not had enough time to investigate much further - upping both northbridge and fsb termination voltages by 0.1v seemed to help a bit, but I'm still not stable at 3.6Ghz / 400 MHz.

So it seems that out of 4 sets of 8400 / p45 chips, 2 are stable at 400MHz with default settings on everything except cpu voltage, and 2 are not.

 

[walk2k]

As long as by "default settings" you mean vcore on "auto" in the AI Overclocker page, mine is stable that way. Heat is a problem though. At 3.6/400 the auto setting does 1.3xx vcore.

I've gotten it down to 1.232v stable (bumped it up 1 more notch after 1 more semi-crash in 1 game). Haven't run Orthos for 24 hours but it's stable for at least 40 minutes on both small and Blend settings. Heat plateaus after about 3-4 minutes anway, if it's stable at that point it's not going to change later on as long as heat remains the same.