Asus P5W-DH vcore fluctuations and instability

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John3

Junior Member
Mar 6, 2003
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Just built a new system and I am rather worried about the stability. I have set the vcore to 1.4625v in the bios, yet speedfan and cpuz show vcore of 1.44v. Also durring orthos stress testing the vcore will momentarily drop to 1.21v in cpuz. Normally I would not be too concerned, but these signs combined with having to use much more vcore than others to achieve similar overclocks make me kinda suspect of the motherboard voltage regulation for the vcore (something that I have read might be an issue on other websites).

for example:
to achieve a speed of:
3.123ghz i need a vcore of 1.60v (66c at load)
3.04ghz - 1.55v
2.96ghz - 1.525v
2.883ghz - 1.50v
2.720ghz - 1.40v (50c at load)

here are the systems specs:
E6400 (L626A472)
Asus P5W-DH
Corsair 6400 2*1gb (4.4.4.12)
evga 7900gt ko
ocz 700watt psu
antec p180 with lots of noisy 120mm fans
zalman cnps9500 led

Things I have tried thus far:

[*]Upping the Vcore (don't want to go past 1.6)
[*]Upping the MCH v to max
[*]Upping the FSB term v to max
[*]Upping the ICH v to max
[*]Upping the mem v to 2.20v
[*]removed the heatsink covers on the north and south bridges
[*]put AS5 on the north and south bridges
[*]removed CPU HSF and redid the AS5 (no change)

A few more items :
the memory I have will reach 463mhz with the 4:5 divider at 4.4.4.12 with 2.10v, can't seem to get beyond that. Also the highest I have gotten the processor fsb is 390mhz (with a vcore of 1.60v). On stock voltage I top out in the 2.603ghz range

At this point after a week of testing I am REALLY thinking about RMAing this board and going the gigabyte route. Does anyone have any ideas?
 
Thor86

Thor86

Diamond Member
May 3, 2001
7,888
7
81
Originally posted by: John3
Just built a new system and I am rather worried about the stability. I have set the vcore to 1.4625v in the bios, yet speedfan and cpuz show vcore of 1.44v. Also durring orthos stress testing the vcore will momentarily drop to 1.21v in cpuz. Normally I would not be too concerned, but these signs combined with having to use much more vcore than others to achieve similar overclocks make me kinda suspect of the motherboard voltage regulation for the vcore (something that I have read might be an issue on other websites).

for example:
to achieve a speed of:
3.123ghz i need a vcore of 1.60v (66c at load)
3.04ghz - 1.55v
2.96ghz - 1.525v
2.883ghz - 1.50v
2.720ghz - 1.40v (50c at load)

here are the systems specs:
E6400 (L626A472)
Asus P5W-DH
Corsair 6400 2*1gb (4.4.4.12)
evga 7900gt ko
ocz 700watt psu
antec p180 with lots of noisy 120mm fans
zalman cnps9500 led

Things I have tried thus far:

1. Upping the Vcore (don't want to go past 1.6)
2. Upping the MCH v to max
3. Upping the FSB term v to max
4. Upping the ICH v to max
5. Upping the mem v to 2.20v
6. removed the heatsink covers on the north and south bridges
7. put AS5 on the north and south bridges
8. removed CPU HSF and redid the AS5 (no change)


One more tidbit :
the memory I have will reach 463mhz with the 4:5 divider at 4.4.4.12 with 2.10v, can't seem to get beyond that. Also the highest I have gotten the processor fsb is 390mhz (with a vcore of 1.60v)

At this point after a week of testing I am REALLY thinking about RMAing this board and going the gigabyte route. Does anyone have any ideas?
Click to expand...

Try this. Set your ram timings to 5-5-5-15-4 and put everything under your voltages to auto, and see what the max overclocks for your cpu is at first by testing using Orthos SP2004 Dual Prime Large FFT testing.

Start slowly, and try 350FSB first and try to keep your ram synced to DDR 800 or less.
 
J

John3

Junior Member
Mar 6, 2003
7
0
0
Ok... seems to be in the neighborhood of 2.603ghz at a FSB of 325. I have run orthos for about 1 hour with no issues.
 
lopri

lopri

Elite Member
Jul 27, 2002
13,310
687
126
I believe it's general behavior of 975X, and certainly the case with my P5W-DH. Unlike A64 overclocking where you can 'divide & conquer', with Intel chipset the voltages required for CPU/RAM/MCH are tightly related to one another. As FSB goes up you may need to adjust voltages for not only the MCH but also the CPU/RAM. For instance in my case;

@266FSB: DDR2-800 CL3 requires 2.2VDIMM
@400FSB: DDR2-800 CL3 requires 2.4VDIMM

As you can see, even though there is no difference as far as memory frequency/timing is concerned, it still needs more voltages.

As for ASUS boards' Vcore fluctuation - That's how it is. (Although the CPU-Z reading of 1.215V is certainly a bug) I haven't seen an ASUS board with solid voltage regulation. Interestingly, while the Vcore tends to drop under load, I found that Vmch and VDIMM actually go up under load.
 
lopri

lopri

Elite Member
Jul 27, 2002
13,310
687
126
Originally posted by: Thor86
Also, use official bios 1305 from Asus, I found this to be the best ocing bios for the board so far, (I've used 0801, 1101).
Click to expand...
Thor, could you share your experience? I just flashed mine and wasn't sure what to expect. I'd greatly appreciate it.

 
Thor86

Thor86

Diamond Member
May 3, 2001
7,888
7
81
Originally posted by: lopri
Originally posted by: Thor86
Also, use official bios 1305 from Asus, I found this to be the best ocing bios for the board so far, (I've used 0801, 1101).
Click to expand...
Thor, could you share your experience? I just flashed mine and wasn't sure what to expect. I'd greatly appreciate it.
Click to expand...

Current setup:

E6400 @ 3.2Ghz, 400fsb, DDR2-800
vcore = 1.375 (1.34 f/l actual reading from Asus Probe)
vdimm = Auto
vmch = 1.55
DRAM timings manual - 5-4-4-15-4 (OCZ Plat XTC Rev.2 PC-6400, 2x1GB)

Currently Orthos dual prime95 running for 18+ hours test.

Using an Antec Trupower 430watt with 20 > 24 pin adapter and 7900GTX. Have not done any 3D testing yet at these bios settings.


 
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