P5B-DX: Nominal Voltages / Auto Mode

Hi2all!

1st part of post is a straight forward question regarding nominal voltage values for the P5B Deluxe AP/WiFi. The BIOS either lists "Auto" or a string of possible values, but there is no telling which value is currently (or most likely) in use or "stock":

Memory Voltage: 1.8 ~ 2.45V
FSB Termination Voltage: 1.2, 1.3, 1.4 and 1.45V
NB Vcore: 1.25, 1.35, 1.45 & 1.55V
SB Vcore (SATA,PCIE): 1.5, 1,6, 1.7 & 1.8V
ICH Chipset: 1.057 & 1.215V

I purposely omitted CPU Vcore since it is dependant on the CPU in use but the above items must have a nominal value which s/b the same for every P5B... . Even DDR2 must have a standard (...1.8V?) value, if I'm not mistaken.

So, can anyone list the nominal values for the Memory/FSB/NB/SB&ICH components please?

While I'm at it, I don't even know at what rate the PCI-E operates at (options range from 90~150MHz), but I'm guessing 100... ?

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Part deux:

When I first fired up the new rig a few weeks back, CPU-Z reported a core voltage of 1.288V which is exactly what I expected to see for my E6400. As I usually like to run my gear "stock" for the first month before starting my OCing adventures, I haven't changed any default BIOS settings (ver 0507) except for setting AI Tuning to manual (def. = auto) & CPU Frequency to 266 (was "default" value anyways). Otherwise, all "advanced" settings are on Auto (incl. all voltage options).

Last night after playing a few levels of F.E.A.R. with all settings maxed out (@40-50fps average ), I decided to let the rig idle all night long & started up ASUS Probe II just to gage the temps. I was however amazed to see a Vcore reading of 1.14V (!) even though I had not set any of ASUS's automated idling functions (GEAR, Nap, A.I. NOS, etc.). I started up Sandra 2007 and ran it's CPU Arithmetic bench a few times and vCore was back up to its nominal value of 1.288V. After the benches were completed, Vcore went back down to 1.14. I verified the figure by running CPU-Z (ASUS Probe was still running).

Can anyone explain why and/or have experienced the same with their setup? I assume that if I manually set Vcore to 1.2875 in BIOS that it will remain at that value, but I don't understand why ASUS is adjusting vCore when it's in Auto mode but "AI Tuning" was set to manual...

Yep, same observation and result here on this mobo but using smithfield D805, not C2D.

When idling, it seems like this mobo is "automatically" lowered the VCore and once needed it will kick in and increase it until max volt limited by the value set at the BIOS.

My D805 VID is 1.315V from factory, but while on stock speed at 2.6Ghz with the VCore set to Auto, it was hovering around idle 1.24V to 1.28V on load and everything is fine like Orthos, Games, double Prime95 etc for hours.

But when I OC it to 3.6Ghz and set the VCore permanently to 1.325V at BIOS, the behaviour is still the same, and at 3.6 it started with 1.26V idle while on Orthos it went up to 1.32V and stable for 24 hours last time I tested it.

Apart from using Probe II, this voltage changes result was verified using DVM with logging feature hooked up on the PWM output using scope's clip at one of those inductor near CPU.

Dunno if this is a feature or a bug ?

bing said:

Yep, same observation and result here on this mobo ... Dunno if this is a feature or a bug ?

Click to expand...

Thx for your i/p, Bing! I guess if it occurs with all P5Bs (& maybe other current ASUS mobos) then it's a feature, not a bug. Still, I wish I was able to turn it on & off myself so that I could at least guarantee that benchmark scores are consistant... . Btw, I am assuming that you are using BIOS v.0507?

P.S. Love what you did with your Matrix Storage Mgr - nice thread!

Well, imo its hardly a bug though and the advantage is the CPU temp is kept optimal instead of constant voltage all the time. Although its nice if they put a small option to make it constant if needed.

Thanks for the nice word on my post, just sharing my experience on the hidden or unexploited power of that matrix thingee, glad you like it !

if you turn off:
spread spectrum, c1e , speedstep technology, and i believe there is one more, it shouldn't change the voltage around anymore

Nope, my D805 doesn't have C1E and EIST and with Spread Spectrum "Disabled" still does the same behaviour.

Oh, yeah, went to all BIOS revision starting from 0204 through the latest 0614.

Interestingly - my P5B - with spread spectrum off, C1E Enabled, EIST Enabled, does reduce to lower multipliers at idle, but always stays at the same voltage (give or take 0.01V) - the voltage measured by probe is 0.05 under that set in bios.

What do I need to enable to get it to drop voltages ?

Mark.

Buckster said:

Interestingly - my P5B - with EIST Enabled, does reduce to lower multipliers at idle...

Click to expand...

Really? Did you select something other than "Desktop" in Window's Power Options Configuration?

bing said:

Nope, my D805 doesn't have C1E and EIST and with Spread Spectrum "Disabled" still does the same behaviour.

Oh, yeah, went to all BIOS revision starting from 0204 through the latest 0614.

Click to expand...

Are you saying that the P5B’s actually change their multiplier on the fly, like throttling down?

I noticed that the ASUS monitor was showing my 6300 at 6x and 7x while CPU-Z consistently said 7x which is stock. I was wondering why the Asus app sometimes showed 6x and other times showed 7x.

Um, how do I turn that off?!

boead said:

I noticed that the ASUS monitor was showing my 6300 at 6x and 7x while CPU-Z consistently said 7x which is stock.

Click to expand...

Okay, I've managed to make a few er, observations.

1. After a fresh boot or reboot (& BIOS voltage parms all on auto), the motherboard allows Vcore to drop (to approx. 1.168 for my E6400) and instantly jumps to 1.288V (stock for E6400) when the CPU gets real work to do (eg. Sandra's arithmetic benchmark). These values were noted with ASUS Probe, Ai Suite and CPU-Z.

2. Boead's comment about ASUS Ai Suite [occasionally] reporting a different multiplier is correct (and a different base speed, eg. 356MHz instead of the stock 266MHz, so that the CPU speed remains a constant value) seems to be a bug in the ASUS software (they never were great application programmers, lol... ). This was verified by CPU-Z which never showed anything other than the expected multiplier, etc.

3. If you use ASUS' Gear app, it will change the voltage based on the selection (from 1.288V at max performance to 1.16V for max power savings mode) but will not throttle upon demand and even though ASUS Probe (or CPU-Z, for that matter), always shows the same CPU speed (2.13 for the E6400), the results from a benchmark are notably degraded from the stock performance.

Resetting the system using Ai Suite's normal button brings the voltage to the fixed stock value (1.288 in the E6400's case) but this throttling-when-idle property noted after a reboot is no longer the case & the voltage remains fixed @stock.

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This makes ASUS' throttle@idle a hidden feature because I've read the userguide from front to back and there is no mention of such a feature... I do like it though and will avoid using Ai Suite all together as this auto-throttle apparently works like a charm. I benched the CPU using Sandra under all conditions and came up with some clear results:

->post-boot & [Gear's] "maximum performance" settings achieve the same scores (~19600 mips / 13600 mflops) however the cpu fan speed is different (1930 and 2100, respectively) and rather annoying above 2K but bringing no advantage over the stock 1930rpm's effectiveness (20-23c above ambient).

->In-between settings like "high performance" are actually detrimental to both performance and cooling (I got 13800/9580 scores and cpu was 26c above ambient, as a result from the fan spinning at only 900rpm!)

->After resetting Gear using the "normal" button, voltage was at a constant 1.288V, the cpu fan @2050 and scores of 19600/13600. So, no better than after a reboot - but without the benefit of this auto-throttling.

So if you want the highest possible rpm, then set Ai Suite's Gear to max performance - otherwise, stay clear of the application and rest assured knowing that the standard post-boot results in as good a benchmark as you can get.