Q6600 & P5Q-EM cold start issues

[walkman_w902]

Hi, guys!

I'm in need of good advice from 775 squad here.

I have good old Q6000 on Asus P5Q-EM motherboard. Usually (I mean for 13 years) it works @2,4 stock as my parents workstation, but recently, since we all got stuck at home, I've decided to OC it. With quite good aftermarket cooling and all the wisdom from forums I've hit 3,5 easily with 1,39 Vcore (1,35625 @ bios) and PLL, FSB and NB voltages at stock values.
The problem comes from my RAM: first 2*2 Gb of KVR800D2N6/2G works fine @935 MHz and 2.00V, but the other pair of same memory (with older manufacturing date) shows error in memtest86 at very first pass. And strangely enough if I choose lower frequency through FSB strap (like 778 MHz) system doesn't even post.
So I've decided to OC my CPU higher to 3,6 and leave RAM 1:1 to FSB 400. I've found minimum stable Vcore 1,448 (1,4000 @ bios), performed Prime95 Blend and OCCT for 1 hour and it works fine. I've played Forza Horizon 3 with constant 100% load on all 4 cores for 3 hours - no sign of instability. Again it works fine with PLL, FSB and NB voltages at stock values.
But at the morning when I tried to start my computer it doesn't even POST - fans are spinning, but no boot image on display. I plugged power cord out for 15 sec, plugged in and it POST. It didn't show any message about overclocking fail and BIOS setting stayed the same. Since then it happens every time when I turn off the system and try to boot it up even immediately after (restarts are fine).
I've tried to investigate it myself and bumped Vcore up to 1,47 (1,43750 @ bios) - no effect. Changed PLL voltage up to 1,56, FSB to 1,34, NB to 1,2 successively - still no effect. I've even tried to bump RAM voltage to 1,9 although it's in stock timings and frequency. I've read many posts about cold start issues but still didn't find a solution
Currently after I plug out and in power cord it looks like I've installed new hardware - it turns on for a few secs without image, then turns off and then boots completely normal.
So what can I do with it?

Sorry for the long post and I'm looking for your wisdom.
TL;DR: Q6600 on Asus P5Q-EM stable @3,6 in tests and games but doesn't POST on a cold start until I plug power cord out and in.

P.S. I don't know if it helps but I wasn't able to run the latest LinX - system powers off without any blue screen. My PSU is be quiet! 500W 80+ Gold and before OC this system works fine with just 275W PSU, so IMHO it's a low possibility that it's a PSU failure.

 

[agent_x007]

I would try with 401MHz on FSB (instead of 400MHz), and setting PCI-e to 101MHz.
What timings you set for memory ?

 

[walkman_w902]

agent_x007
MB automatically set PCI-e to 103 when I hit 400 FSB and don't allow lower values. I've tried to set 411 and 405 FSB on this voltages - system loads just fine, but blue screens when I run Prime95. I suppose 3,7 is possible on my chip, just need higher Vcore. But the main issue stays the same on such FSB values - it doesn't POST until I plug out/in.
Memory are at stock 6-6-6-18, everything else is on Auto, DRAM voltages 1,8/1,9 or even Auto.

 

[Regeneration]

I remember ASUS X38 motherboards having weird bugs like this one. Never found a solution. Sometimes will just no POST for no reason.

Try to set all BIOS settings manually. Especially memory timings. Don't leave anything on Auto.

 

[agent_x007]

^This is G45 based ?

OP : Try using 1,9V on DRAM at 400MHz FSB, and DRAM Freq. = 800MHz CL5.5.5.18 timings.
Not having PCI-e control over 400Mhz FSB is worrying though...
It can be also a fault of BIOS in secondary timings... (like too low tRFC).

PS. Running latest LinX on Q6600 at ~1,44V under load with naked 4-phase VRM is kinda brave (unless you have direct airflow over MOSFETs). The good news is you have two Low side MOSFETs per phase and apparently working overheat protection

PS2. I'm guessing this is G0 stepping, since it went to 3,5GHz without major issues ?

 

[walkman_w902]

^Set 5-5-5-18 @1,9V. tRFC on Auto was 52, tried 130 - starts fine, reboots fine, turn it off and on - no POST. Plug out and in - freeze on Windows logo, rebooted manually, get "Overclocking failed" message. Tried to manually set tRFC on 50 - same POST thing, but loads normally after. Don't think it's a RAM issue though.

And sure thats a G0. My MB is famous for hot north bridge (and 4-phase VRM as you stated), so I went for top-flow CPU cooler (be quiet! Dark Rock TF as a best possible option for me - 2*140mm fans to VRM, 220 TDP stated). Max temperature in Prime95 Blend was 84C, Small FFT was 85. LinX @3,5 and 1.39V was 89C and I thought it was the limit, but have to go higher due to return my memory to 400. NB is hot, but I can put my finger to it, so I think it's like 55-60C. I know that LinX overloads CPU up to 130% from Intel temperature guide, so I tried it once @3,6 and the ignored it.

Regeneration
So, there could be the same problem on P5Q3 deluxe or Maximus II Extreme? They are X38 if I remember correctly.

 

[Regeneration]

Regeneration
So, there could be the same problem on P5Q3 deluxe or Maximus II Extreme? They are X38 if I remember correctly.

Yes, despite OC being 1000% stable, time to time, BIOS gives overclock errors and resets to defaults. Usually happens on cold reboots and when powered on.

 

[agent_x007]

Both P5Q3 and Maximus II are P45 based (OP's board is G45)...

Hmm... maybe it's a FSB hole then ?
You should try 380-399MHz FSB range - just as test.
Changing strap (266/333/400) - should answer if it's chipset related, but I don't think you have that option...
Maybe try disabling Static Read and setting Transaction Booster to 9 (IF you have those) ?

Also, 4x2GB is pretty hard on memory controller, so giving it a 1,25V-1,35V is a good idea (assuming it doesn't overheat and stability goes to hell).

 

[Regeneration]

P45, P35, X38, X48. All of ASUS 775 motherboards even high-end ones like Maximum Extreme.

Pass 48 hours of Prime95, MemTest86, IBT, everything works 100% fine.

You power up the next day and get this stupid message:

I spent days trying to figure out why this happen. Never found a solution or a reason.

Doesn't happen on Gigabyte motherboards.

 

[walkman_w902]

389*9 works fine (3,5 GHz) as I stated, cold boot - OK. Have that setting for a 1,5 month until I got another pair of RAM which errors on 935 MHz in memtest. Both refused to boot at 778 MHz and even when I tried 399 FSB (799 MHz).

 

[agent_x007]

Well, either way you can't expect NB to work with 4x2GB the same as did with 2x2GB (since I bet you plan on using ALL RAM you have, instead of trying to find a pair that works at old settings ?).

Personally, I would stop at 3,5-3,59GHz (to avoid no boot + make VRM work a bit easier), and make this setting stable with 4x2GB memory configuration (regardless of DRAM frequency required).
Again : Keeping higher FSB with all DIMMs used IS NOT easy, especially on Gxx series.

@Regeneration I guessing CMOS bats were fine, and you didin't cut power to PSU in any point for entire night ?

 

[walkman_w902]

Yeah, looks like I have to go that way and make my RAM work somehow at 935 (besides I've managed to boot normally with 960 MHz, but not cold boot).
I know that my MB hit FSB wall at 425 MHz, but for me it didn't work out even with 8 multiplier (400*8).
266*9 as stock 2,4 GHz works fine with all 4*2GB, no signs of errors, cold boot fine.

I'm planning to clear CMOS and try it for the last time from scratch, may be I should set voltages simultaneously (not separately as before), what do you think, guys:
Vcore - 1.45 (can go a little bit higher, just for the cold boot test)
PLL - should I try higher than 1.56? Like 1.60, but no more I suppose.
FSB termination - 1,24 (or should I bump it up to 1,34, since it's a Quad?)
NB - honestly, don't know at all. 1,2V didn't work out, yellow zone starts from 1,28 and I'm afraid of overheating it since it is a weakest spot.
DRAM - 1,9V with 5-5-5-18, static read training - disabled, Ai Performance level - 11, maybe?

I would try to do it with trusted 2*2 Gb to see if it's make a difference.

Performed extensive testing with 2*2 GB Samsung DDR2, which works OK at frequencies lower than 800.
Such cold boot issues start to happen when I moved over 393-394 FSB and they didn't gone when I went full retard (never went full retard!!!) and set 416 FSB with Vcore 1.47, PLL 1.6, FSB 1.34, NB 1.2 - was able to load normally, but no help with cold boot.
So I would go back to 389 FSB and try to make my Kingston work at 935 without errors.