Read First Before Increasing Voltages!

No_Style

In the midst of high overclocking P4s, I've noticed a lot of individuals stepping over the max tolerables for their CPUs.

[COLOR=Orange]Intel [/COLOR]

Intel Celeron(R) Processor up to 1.10 GHz
Section 2.9 - Table 4 states:
Max Voltage: [Typical Operating voltage from Table 5] V + 0.1 V = [MaxVCore] V

Intel Celeron Processor for the PGA370 Socket up to 1.40 GHz on 0.13 Micron Process
Section 2.10 - Table 6 states:
Max Voltage: 1.75 V

Intel(R) Celeron Processor in the 478-Pin Package at 1.80 GHz
Section 2.9 - Table 5 states:
Max Voltage: 2.10 V

Intel Celeron Processor on 0.13 Micron Process in the 478-Pin Package
Section 2.10 - Table 6 states:
Max Voltage: 1.75 V

Intel Celeron D Processors 335, 330, 325, and 320
Section 2.10 - Table 2-7 states:
Max Voltage: 1.55 V

Coppermine Documentation (500 MHz to 1.13 GHz)
Section 2.9 - Table 6 states:
Max Voltage: 2.10 V

Intel Pentium 4 Processor in the 423-pin Package at 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90 and 2 GHz (Willamette Socket 423)
Section 2.9 - Table 4 states:
Max Voltage: 2.10 V

Intel Pentium 4 Processor in the 478-pin Package at 1.40 GHz, 1.50 GHz, 1.60 GHz, 1.70 GHz, 1.80 GHz, 1.90 GHz, and 2 GHz (Willamette Socket 478)
Section 2.10 - Table 5 states:
Max Voltage: 2.10 V

Intel Pentium 4 Processor with 512-KB L2 Cache on 0.13 Micron Process and Intel Pentium 4 Processor Extreme Edition Supporting Hyper-Threading Technology Documentation (Northwood)
Section 2.10 - Table 2-5 states:
Max Voltage: 1.75 V

Intel Pentium 4 Processor on 90 nm Process Documentation (Prescott)
Section 2.9 - Table 8 states:
Max Voltage: 1.55 V

Mobile Intel Pentium 4 Documentation
Section 2.10 - Table 6 states:
Max Voltage: 1.75 V

Mobile Intel Pentium M Documentation (Centrino)
Section 3.9 - Table 4 states:
Max Voltage: 1.75 V

Intel Pentium M Processor on 90nm Process with 2-MB L2 Cache Documentation
Section 3.8 - Table 4 states:
Max Voltage: 1.55 V

Intel Pentium 4 Processor 560, 550, 540, 530 and 520
Section 2.10 - Table 2-7 states:
Max Voltage: 1.55 V

Intel Pentium 4 Processor Extreme Edition on 0.13 Micron Process in the 775-Land Package
Section 2.10 - Table 2-4 states:
Max Voltage: 1.55 V

[COLOR=Green] AMD [/COLOR]

AMD Duron 600 MHz to 950 MHz
Section 7.9 - Table 8 States:
Max Voltage: 1.7 V

AMD Duron 900 MHz to 1300 MHz
Section 7.8 - Table 7 States:
Max Voltage: 1.75 V + 0.5 V = 2.25 V

AMD Duron 1400 MHz to 1800 Mhz
Section 7.8 - Table 7 States:
Max Voltage: 1.5 V + 0.5 V = 2.0 V

AMD Athlon XP 1500+ to 2100+
Section 6 - Table 1 States:
Max Voltage: 1.75 V + 0.5 V = 2.25 V

AMD Athlon XP With 266 FSB (1700+ to 2200+)
Section 8.8 - Table 13 States
Max Voltage: 1.65 V + 0.5 V = 2.15 V

AMD Athlon XP With 333 FSB (2500+ to 3000+)
Section 8.8 - Table 14 States:
Max Voltage: 1.65 V + 0.5 V = 2.15 V

AMD Athlon XP With 400 FSB (3000+ to 3200+)
Section 8.8 - Table 14 States:
Max Voltage: 1.65 V + 0.5 V = 2.15 V

I hope this will save a lot of angst, money loss and wasted time to all overclockers out there. It does not matter if you have low core temperatures, the fact that the processor is receiving a higher voltage than it is capable of handling, deteriorates it. Remember, just because the voltage is set at 1.65 V, it does not necessarily mean the actual voltage rating is 1.65 V (Asus boards are notorious for not obeying their set VCore). I suggest everybody who's overclocking give the documentaion a quick read.

Keep that voltage low

**Note: There is certainly more than just mere voltages that will regulate the health of your processor. AMD processors have high max voltages, but within their documentation there is also thermal power to consider.

UPDATE: I've updated the real absolute max. Thanks to the inquiry from Jazzyjazz2004. I've must have misread somewhere. The update should make more sense now. Sorry for confusion.

UPDATE 2 (9/3/04): Added Mobile Pentium 4 and Pentium M max voltage info.

UPDATE 3 (6/4/04): Added Prescott Max Voltage Info

UPDATE 4 (3/9/04): Added Duron Max Voltage Info and Celeron, LGA775 max voltage info. Fixed some minor typoes.

UPDATE 5 (30/10/04): Fixed addition errors.

HardWired

Couldn't agree more about keeping the volts low...that's some good info for others.

I've read from many overclockers not to even go over 1.70 for any great length of time w/ Northwood chips, regardless of Intel's stated 1.75 max. I use a P4PE also, and I'm able to get 3.3GHz out of my 2.53b multivid at 1.525, even though the board overvolts it to 1.632.

I could get 3.4GHz or higher stable(ran it that way for a short while...even 3.5GHz) at 1.65+, but I don't want to flirt with that 1.70 threshold. I've seen it referred to as "Sudden Northwood Death Syndrome" or SNDS. It a slow but sure failure over a couple of days or weeks and has been attributed to running at or over 1.70 vcore.

I can only afford an upgrade every 6mo. to a year, so I'm keeping this one at a low vcore and am very happy with my 800 MHz o'c.

No_Style

This information is not apparent. The "manual" for the Intel Chips that come in boxes or whatnot, do not show you any of this stuff. This info seems to be purely online.

No_Style

God Damn. This is sticky worthy isn't?

No_Style

I'm kissing the 1.7 V threshold right now. It fluxes to that mark every so often. Living life on the edge.

Necrosis

Indeed it is true, and I'm not sure about your 50% tolerance though. Usually for components it's around 10%. What this is called is dielectric breakdown. Basically every diode, transistor has a certain voltage where it starts to break down. It is sometimes used to limit flow, so intentionally done on purpose in the normal operation of a circuit. I've noticed with my board there is indeed a .5 variant in Vcore voltage. I had it set at 1.7 (1.74 - 1.75 in MBM) and noticed my full load temps were awfully high. Now it's set at 1.65, and hits around 1.71 in MBM with a full load temp for 2 hours of 43C. I'm taking these temps. from the diode not underneath the socket.

JCLW

1.75 is the accepted max voltage for Tullies, but I've yet to see a Tualatin core die from anything except a pin mod gone bad. Mine barely hits 40C @ 1.825v, which is the max vcore a VRM 8.5 spec board will supply.

- JW

Warpy

Hi

From looking at the spec docos my cpu isnt capable of overclocking!!

I heard some bad news about the 2200+ - Also noticed that not many ppl have them.

I wonder why they released the chip in so far as being so different to the others?

B

NucleuZ

I gotta get myself one of those P4 2,4C or 2,6C...they seem to overclock nicely.

I read that once you reach top overclocking levels, you should go down with the voltagelevels. Also higher voltage doesn't always mean higher overclocking levels.

tastyweat

Some decent info there mate - luckily - I don't have to adjust my volts atm

2800barton @ 200x11 on 1.65v

Sharkims

On the newer P4 boxes it's rather apparent. 2.4c - "MAX VOLTAGES: 1.525v" 3.0c "MAX VOLTAGES: 1.55v"

My personal experience with this 2.4c is I am more stable at 1.525v than I am at 1.55v+. So, this is very, VERY true.

Jazzyjazz2004

"AMD Athlon XP With 333 FSB (2500+ to 3000+)
Section 6.4 - Table 4 states:
Max Voltage: 1.5 x (50%) 1.65 V = 2.475 V"

I downloaded the PDF file and cannot decipher where you derived this formula yielding the max voltage is 2.475V. Yes, I went to the correct section and table.
Are you saying that it is SAFE to run my Athlon XP 2500 at 2.475 V?

Jazz

No_Style

Sorry about the confusion, I looked at the docs again and I realized I was looking at the wrong place. Sorry for confusion. It's updated now. Thanks Jazz~!

Jazzyjazz2004

Here I come 1.95 (safety margin). I currently run Athlon XP 2500 at 12.5x185@1.75...smokin'!

Zardon

running my barton @ 1.93 v 2500mhz, probably shorten its lifespan but the performance is smokin

Jazzyjazz2004

LOL... I can imagine that it's smokin'!

I stopped at 185x12.5 not only because my memory is maxed at at 2-2-2-2-6 (is that too many 2's?) but because any subsequent raising of the overclock using just the multiplier required such a large voltage increase that I didn't feel the additional 100 to 200 Mhz was worth it.

For instance;
I got 479 Mhz increase (from default 1833 Mhz to 2312 Mhz) for a 0.10 voltage increase (1.65V to 1.75V)...but to go ANOTHER 100 Mhz needs another +0.1 V, for a total of 1.85V... an additional 200 Mhz requires a grand total of 1.95V. The extra 100 to 200 Mhz didn't seem worht it, especially since my 3d Benchmarks stayed the same. I suspect my graphics card is my current bottleneck and I need an upgrade.

Jazz...and PEACE to You!

G@MeBoY

running my XP2000 at 10x230@2.0 for 4 months, not smokin' ...not diein' to jazzyjazz : cant you lower multiplier and go for FSB speed ? FSB will give you more increase than 100mhz on CPU. Better to have 230FSB with loosen memory latency settings and 2ghz CPU, than 2.3Ghz CPU with 190FSB...

No_Style

Anybody want to help me with finding the documentation for the Athlon XP-Ms or determining Athlon 64 (Opteron, FX, Regular) max voltages? I can't seem to determine what the max is for 64 bit chips, and finding XP-M documentation was taking me in circles over at AMD's homepage.

Jazzyjazz2004

Yes, I have tried upping the FSB and lowering the multi, but system becomes unstable...I need faster clocking memory. Jazz

G@MeBoY

To jazz: set vdd voltage to 2.0V and you'll do fine, if not set vdimm voltage to 2.9V...Corsair MUST do it

Roadee

Not only will the higher voltages decrease the life span of the CPU, but it will also shorten the lifespan of the MB. High FSB and voltages will add undo heat to many of the circuits of the MB to include the Mosfets. Many of the NF2 boards are well known for the Mosfets overheating, and this in turn causes unstable voltages, in which can cause instability and occasionally damage to computer components.

I would NEVER suggest to anyone that they run at such a high voltage unless they are using extreme cooling solutions on ALL components involved. Which would include high end water cooling, passive cooling on the south bridge, increased cooling on the north bridge, passive cooling on the mosfets, as well as the other components involved to include increased case cooling.

Overclocking is fun for the experienced, EXPENSIVE for the non-experienced.

No_Style

Excellent line. Hence, the reason I posted the info here.

G@MeBoY

This is OC and modding section of forum, is it ? Jazzyjazz is not unexperienced user, so I suggested higher voltages to him, thus, only for testing purposes. Nothing's gonna get friend in 15 mins, and the life span of CPU will get reduced from 100 years to 10 years (guessing) . In 10 years you an I and everyone will change at least 1 CPU. But, what Roadee said is true and bare that in mind when OC-ing, ALLWAYS CHECK temps in regular bases, if you notice that something is too hot, either cool it more or lower the voltage/clock And of course, there is allways an option to higher the latency's of memory instead of raising the Vdimm voltage, on nForce2 boards not much is lost with higher latency. I would personally rather use 230FSB with 3-3-3-11 than 200FSB with 2-2-2-11 (talking about nForce2 chipset).

Zardon

This is far from being a "new" article and im sure alot of you have read it already (some of it is outdated I know but its interesting to look back), but for those who havent this makes interesting reading here and here as well