Is 1.65v VMCH safe?

[Mr.X]

My previous settings were :
378 x 9 = 3402Mhz, v-core 1.41
Ram was running at 1:1, vdim 1.9v
Vmch 1.55

I decided to change those as I realised I kept failling Orthos within 3 minutes at 1.41v and 1.42v (this wan't the case a few months ago though).

I set my multi to 8 and FBS to 425 (vcore 1.45, vdim 2.0v) but it wouldn't boot above 410mhz at vmch 1.60v so I raised it to 1.65. and I've been running Orthos for 3 hours without any problems.

Anyway, my question is: Is 1.65v safe for 24/7 usage or should I go back to 378 x 9 and 1.55v?

[The Nemesis]

1.65vmch is safe for 24/7 use though use of the heatpipe fan &/or good case airflow would be recommended. Active cooling is required for 1.85vmch (not what shipped with board), but I wouldn't go above 1.7vmch without active cooling.

[anarinsk]

There might be no problem at 1.67V on MCH. But, you should equip another fan for safety.

[Mr.X]

I already have one 20mm fan both on the north and south bridge. Temperature is no problem. My concern is whether there will be a problem due to overvoltage in the long run.

PS: 1.65v is the max setting I can set anyway.

[X_Man]

What does uping the voltage on the MCP actually do?

[Bigchrome]

Increases stabiltity at higher fsb. I run 2v constantly btw.

[X_Man]

Ahhh! Since I am in the 430MHz range - I can up my CPU voltage to get me 1800MHz (Just high enough to boot windows) and tweak the MCP voltage from there to achieve stability during benchmarks?

Also, not to hijack Mr X's thread, I guess his question is what are the long term effects of running MCP at say 2.0v (my 680i max'ed out at 1.75v).

[Bigchrome]

Long term effect is the board gets dead. 680i at 1.75 is a diff story as it's a different chipset.

[Leeghoofd]

my P5W had no issues booting up at 400mhz with 1.55v MCP bundled with my E6400, after a few months though I needed more volts to keep it stable, I had to put 1.65 to get it stable again, now 1 month later max FSB I get is 300mhz anything above thatit still boots into windows but orthos or prilme fails in a minute. Board is dying, it was cooled all the time, 120mm at the southbridge and at 5cm fan on the northbridge. I hope yours ain't dying either...

[fgw]

Intel 975X Express Chipset MCH - Datasheet
http://developer.intel.com/design/chipsets/datashts/310158.htm


Table 10-1. Absolute Minimum and Maximum Ratings
MCH Core Supply Voltage with respect to VSS Min=–0.3V Max=1.65V

Table 10-5. DC Characteristics
MCH Core Supply Voltage Min=1.425V Typ=1.50V Max=1.575V


Table 10-1 specifies absolute maximum and minimum ratings only and lie outside the functional limits of the processor. Within functional operation limits, functionality and long-term reliability can be expected.
At conditions outside functional operation condition limits, but within absolute maximum and minimum ratings, neither functionality nor long-term reliability can be expected. If a device is returned to conditions within functional operation limits after having been subjected to conditions outside these limits, but within the absolute maximum and minimum ratings, the device may be functional, but with its lifetime degraded depending on exposure to conditions exceeding the functional operation condition limits.
At conditions exceeding absolute maximum and minimum ratings, neither functionality nor long-term reliability can be expected. Moreover, if a device is subjected to these conditions for any length of time then, when returned to conditions within the functional operating condition limits, it will either not function, or its reliability will be severely degraded.

[orion23]

What do you guys mean by safe?

Safe that the motherboard will die?

or Safe that the board will catch on fire?

[JWilson]

The 965 chip is even lower. Data sheet says 1.35V max....

[fgw]

The 965 chip is even lower. Data sheet says 1.35V max....

you'r right man! i'm using a 975X on my abit, hope nobody gots confused ...

[JWilson]

And to top it off, the Biostar 965PT overvolts it's Vmch, so with the BIOS set to 1.55v, it puts out 1.85v!

I've used the high setting, but scares me :D

[fgw]

And to top it off, the Biostar 965PT overvolts it's Vmch, so with the BIOS set to 1.55v, it puts out 1.85v!

thats strange! have not heard about overvolting until now. most of the time its the other way round.

my stock abit aw9d-max (975X) showed vmch of 1.65V in bios while i measured 1.56V under load! thats a drop of nearly 0,1V!

but there is still the question: how far can we go, because from what i have seen so far: vmch is the key to higher fsb. at least on 975X.

[heikis]

And to top it off, the Biostar 965PT overvolts it's Vmch, so with the BIOS set to 1.55v, it puts out 1.85v!

I've used the high setting, but scares me :D

sry, but i dont believe you. please tell us, how you measured the voltage.

[JWilson]

Use a digital multimeter and measure it yourself.

[Bail_w]

1.67 is kind of alot for 24/7 to me. for me i will not try to go over 1.6v.