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E6750 on GA-N650SLI-DS4: big OC issues

post #1 of 6
Thread Starter 
First off, system specs:

Core 2 Duo E6750 w/ Freezer 7 Pro
Gigabyte GA-N650SLI-DS4
2x1GB Crucial Ballistix DDR2-800
eVGA 8800GTS 320MB

I know the P35 boards would have been better overclockers from the start, but I figured the 650i SLI board would be nice for the SLI option, plus I can make use of the dual IDE host ports. Unfortunately, though, things haven't been going so well - I suspect the culprit is the mobo, but I'm not 100% sure. I'm hoping you guys could help me pinpoint the cause before I RMA this board and go get a P35-DS3R (and a SATA DVD burner).

My basic oc'ing experience thus far looks like this:

Stock speeds (333x8 2.66GHz, DDR2 800MHz 5-5-5-15): 8hr Orthos blend stable.
367x8 (2.93GHz), 1:1 synced DDR2 (734MHz 5-5-5-15): Orthos small stable. Orthos large/blend freezes system.
372x8 (2.97GHz), 1:1 synced DDR2 (744MHz 5-5-5-15): Orthos small stable. Orthos large/blend freezes system.
375x8 (3.00 GHz), 1:1 synced DDR2 (750MHz 5-5-5-15): I had this Windows boot/10min Orthos small stable once or twice. Usually less stable than that.
380x8, 390x8, or 400x8 (with synced DDR2 speeds 760, 780, 800): fail to POST.

(fyi, 'freeze' doesn't mean Orthos error, or BSOD - it means hard lockup, no response to kb/mouse whatsoever, no choice but power off)

I've also tried most of these FSB values with the RAM unlinked and running at 800MHz, but it's generally the same or worse stability.

The main reason I suspect it's the mobo is that Orthos small running okay but Orthos blend freezing implies a problem with using the RAM, but I know the RAM is pretty solid - I ran the overnight stock-speed blend with it at 800MHz 5-5-5-15 @ 1.92v, but when I go to a 367 FSB, it suddenly can't run at 734 5-5-5-15 with anything from 1.92 to 2.12v?

I know my CPU is (relatively) stable at 375 FSB, I know my ram is stable at 800MHz, so I can't help but believe the weak link here is the motherboard, most likely the northbridge. Adding volts to the NB/FSB is even more tricky: one single time I posted at 380 FSB with +0.2v northbridge and +0.3v FSB, but other times, I'll try adding +0.05v NB/+0.1v FSB to stabilize at 367 FSB but the system will post, display the CPU info, then freeze! Sometimes I can power off, wait a while, power back on and at least get into BIOS to reverse it - more often though, it means a CMOS clear.

Another interesting tidbit: there are two distinct FSB holes you can see in the BIOS. Any setting from 362-366 will have an effective FSB of 361.6, and anything from 367-371 is an effective 367. At 372 it goes back to normal. I think I tried 360 once and it failed to post, so I'm wondering if these holes are because of transferring to different straps (eg. 360 is at the high end of a strap and is unstable, 367/372 are lower ends of a looser strap and at least can post/boot Windows).

So anyway, I'm hoping someone more experienced can tell me if I'm right in blaming the northbridge for my troubles, or if there are other things I should try to narrow down the problem more. I still have a week or two on the refund period for the mobo, so I can do some more testing if need be. If it is the mobo, then I have to evaluate whether the $$ for RMA/new mobo/buying a SATA DVD burner is worth the OC to me, plus the downtime and issues I might have transferring my XP install.
post #2 of 6
this kind of sounds mobo-esque. with any of the 6 series mobos its really hit or miss, in my experience with them.

what are your temps like?

*edit: and how big is your power supply?
post #3 of 6
Thread Starter 
Quote:
Originally Posted by antesignani View Post
this kind of sounds mobo-esque. with any of the 6 series mobos its really hit or miss, in my experience with them.

what are your temps like?

*edit: and how big is your power supply?
Corsair 520W, and even at the highest Orthos load I could test (3GHz) my cpu temp wasn't breaking 57C. Case temp was somewhere in the 40s, and I don't think there was a sensor for NB temp, which might have been helpful - I know the 6 series NB runs pretty hot, and this board in particular always got complaints about the heatsink being very hot to the touch. I tried running with open case and an 80mm fan resting on top of the NB heatsink, but it didn't really improve stability much.
post #4 of 6
I see you mention you're increasing the NB/SB voltages, but what about the cpu's voltage? Have you tweaked that any?
R'lyeh
(13 items)
 
  
CPUMotherboardGraphicsRAM
Q9550 (4.03GHz) Gigabyte EP45-UD3P EVGA GTX285 4GB (2x2) Corsair Dominator (5-5-5-15, 2.1v) 
Hard DriveOptical DriveOSMonitor
300GB WD VelociRaptor, 320GB WD Caviar 7200 Lite-On 20X DVD+R Ubuntu 10.04 x64 / Vista Home Premium x64 Samsung 226BW 
KeyboardPowerCaseMouse
Generic P/S2 Corsair HX750W Lian-Li V2000 Logitech G3 
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R'lyeh
(13 items)
 
  
CPUMotherboardGraphicsRAM
Q9550 (4.03GHz) Gigabyte EP45-UD3P EVGA GTX285 4GB (2x2) Corsair Dominator (5-5-5-15, 2.1v) 
Hard DriveOptical DriveOSMonitor
300GB WD VelociRaptor, 320GB WD Caviar 7200 Lite-On 20X DVD+R Ubuntu 10.04 x64 / Vista Home Premium x64 Samsung 226BW 
KeyboardPowerCaseMouse
Generic P/S2 Corsair HX750W Lian-Li V2000 Logitech G3 
  hide details  
Reply
post #5 of 6
Thread Starter 
Quote:
Originally Posted by afzsom View Post
I see you mention you're increasing the NB/SB voltages, but what about the cpu's voltage? Have you tweaked that any?
I went up to 1.45v for the 3GHz, but I think even that was probably overkill. That's why I really think it is a northbridge issue, since at the exact same FSB settings I can stress my CPU with Orthos small and not have a single problem, but as soon as I put any combined CPU/RAM stress with large or blend, it crashes within a minute.
post #6 of 6
Yea, it seems like the voltages and timings all are right on track to hit the speeds you're trying. Sorry I can't be of more help, someone else with more experience should be along shortly.
R'lyeh
(13 items)
 
  
CPUMotherboardGraphicsRAM
Q9550 (4.03GHz) Gigabyte EP45-UD3P EVGA GTX285 4GB (2x2) Corsair Dominator (5-5-5-15, 2.1v) 
Hard DriveOptical DriveOSMonitor
300GB WD VelociRaptor, 320GB WD Caviar 7200 Lite-On 20X DVD+R Ubuntu 10.04 x64 / Vista Home Premium x64 Samsung 226BW 
KeyboardPowerCaseMouse
Generic P/S2 Corsair HX750W Lian-Li V2000 Logitech G3 
  hide details  
Reply
R'lyeh
(13 items)
 
  
CPUMotherboardGraphicsRAM
Q9550 (4.03GHz) Gigabyte EP45-UD3P EVGA GTX285 4GB (2x2) Corsair Dominator (5-5-5-15, 2.1v) 
Hard DriveOptical DriveOSMonitor
300GB WD VelociRaptor, 320GB WD Caviar 7200 Lite-On 20X DVD+R Ubuntu 10.04 x64 / Vista Home Premium x64 Samsung 226BW 
KeyboardPowerCaseMouse
Generic P/S2 Corsair HX750W Lian-Li V2000 Logitech G3 
  hide details  
Reply
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