I did a quick look in my manual (paper one included with my ASUS A8V
Deluxe, Ver. 2 Circa December, it has a BIOS "1009" on it I think, because
that is what it says on the EEPROM sticker) and I only saw one reference,
on page 4-28 where it says DDR options: "[auto] [2.6] [2.7] 2.8]". Does
that mean that I can't raise my memory voltage to 3 volts, or higher?
Does that option change with newer BIOS versions?
What about my CPU max voltage, what is it, and is that controlled by the
BIOS version (my understanding is that it is with some limitation).
If I update to version 1013/1014 beta, then what will my max voltages be
for my system RAM and my CPU?
Can someone help illuminate this for me?
To start with, a voltage setting cannot go higher than the hardware
design allows for. For example, the DIMM voltage on some Asus boards,
is done with an op-amp based linear regulator, and in fact there aren't
even three settings in the hardware (perhaps there are two). So,
while the BIOS may offer a comforting set of values, the hardware
doesn't necessarily have to match. In your example above, maybe both
the 2.6 and 2.7 setting result in 2.6V output - only observation with
any hardware voltage monitoring, is going to tell you what is happening.
Since Vdimm is not one of the monitored voltages on your board, you
would need a voltmeter to measure the actual voltage being used.
The Vcore situation is a bit different, because a standards compliant
switching regulator is used. If AMD defines 0.8 to 1.55V as the range
of voltages for the K8 family, then that is the range that will be
supported by the chip. If Asus offers voltages outside that range,
it could be achieved by means of fooling around with an offset pin
on the regulator chip, to adjust the voltage upward. Again, use the
voltage monitor in the BIOS or Asus Probe, to know whether anything
is actually happening when a higher voltage is selected. (I must
confess that I'm puzzled how all this can work, because you would
want programs like clockgen, CPUZ, NVtune, all sorts of Windows
utilities to return valid voltage values, and I don't know how
you can extend a Vcore circuit voltage range, and allow utilities
like that to accurately reflect the setting.)
So, to start with, you need to reverse engineer the chips on the
motherboard, to understand the hardware limits. The BIOS is just
another layer of confusion added on top, as the BIOS may or may
not be reflecting what the hardware can do.
As a general rule, don't expect a BIOS update to offer new voltages.
I think I have seen one BIOS released by Asus, that added a voltage
value to the BIOS interface, so it can happen, but it is not a
common occurrence.
The hardware itself has limits. 2.8V is probably considered a
safe generic overvoltage for your average DIMM, so Asus doesn't
consider that they will be liable if any user burns out a DIMM.
If you had a DFI board that offered 4.0V, there is every
possibility that either through a BIOS bug (value gets set to
4V by a BIOS bug), or a noob user jamming the control to max,
will result in the killing of DIMMs. I'm sure DFI has plenty of
disclaimers, that whatever you do, it is your fault.
Asus is more conservative, and tends to pay attention to the spec
limits for hardware. For example, the Athlon64 has a max DIMM voltage
of 2.9V, so don't expect Asus to provide voltages above that
value. (I don't know of a way to predict the headroom that is
actually available on Vdimm - it really depends on I/O protection
structures, and it can also depend on how the various power
rings are connected together by parasitic structures inside the
chip. When boosting a voltage to artificially high values, you could in
fact be causing current to flow through paths in the chip,
that is wasn't intended to go through - parasitic paths
are ones that are created by using conditions outside the operating
voltage specs.)
Various private forums on the net, offer volt mods for Vdimm and
Vcore. If you are determined to "go to the wall", that is one
way to get what you want. Or, perhaps a DFI or Abit motherboard
is the way to go.
Wire tricks (placing a wire between certain pins in the socket),
only helps if the Vcore defined for the processor has some range
left in it. If the K8 VID table only goes to 1.55V, then a wire
trick cannot offer more than 1.55V. An actual volt mod can do it,
but is dangerous - this thread proves you should do mods to your
own board, not let someone else do it:
http://www.xtremesystems.org/forums/showthread.php?t=40378&highlight=a8v
The purpose of Asus boards, is to offer broad compatibility with
stuff like DIMMs, and easy out-of-the-box auto-everything setup
by the user. Asus boards are not the optimum solution, if you
also want to overvolt (or undervolt) stuff.
HTH,
Paul
