Thus spake Paul:
> In article <(E-Mail Removed)>, "Paul Busby"
> <(E-Mail Removed)> wrote:
>
>> I ordered 2 sticks of Crucial 512MB PC3200 RAM last Sunday & fitted
>> them Tuesday night. having removed 2 sticks of Crucial 256MB PC2100
>> which ran with slack timings @172MHz, 1:1, 12.5x & 1.575V.
>>
>> Entered the bios & set the FSB to 200MHz with a multiplier of 10x,
>> upped the CPU supply to ~1.75V then rebooted - XP blue screened.
>> Upped the RAM to 2.7V & again crashed. Set the FSB to 190MHz & XP
>> booted but was very unstable & remained so after changing other
>> settings. The system became stable @ 177MHz - only a little more
>> than I was able to achieve with the PC2100!
>>
>> I value XP's ACPI S3 Standby mode but if I don't set System
>> Performance to Optimal in the bios (modded 1013), I loose it. I
>> ended up setting the FSB to 166MHz & thought through what further
>> settings I could tweak to get 200MHz FSB & retain S3 Standby.
>>
>> Pulled out one stick of RAM then reset the FSB to 200 then booted
>> straight into Memtest86 @ 7.5x. Got through a single run then
>> repeated with the RAM back in dual channel mode but in different
>> slots, again Memtest86 passed. Rebooted into XP & blue screen. Set
>> the 2 sticks in single channel & XP booted fine. Set 11.5x, Prime95
>> & everything else runs fine with my Zalman 7000Cu set for 1700rpm
>> for temps between 50C idle (Case 28) & 60 running burnk7- a little
>> high but the fan still has plenty of headroom. The CPU is set to
>> 1.75V & would need to raise it to get to 2400MHz with a consequent
>> increase in noise.
>>
>> Anyone care to speculate why dual channel mode won't run at all @
>> 200MHz at any multiplier? I'll try the unmodded 1013 bios just to
>> check it's not that. Not a huge loss but it would be nice to get it
>> working without going to LL RAM with its heavy price premium & small
>> gain in performance for my usage.
>
> It could be a chip design limitation. Imagine 160 or more output
> signals switching simultaneously. That is a significant electrical
> disturbance, and amps of current flow into or out of the chip during
> a transition. (The normal solution to this problem, is to add more
> pins to a chip, like what happened to the LGA775 processor socket.
> But adding more power and ground signals, increases the cost of the
> chipset. In
> the case of a LGA775 processor, the extra pins are there due to the
> sheer number of DC amps flowing into the chip, as much as anything
> else.)
>
> With your mobile, you have many options for accomodating the RAM.
> By keeping the CPU:Mem ratio 1:1, running the memory at whatever
> speed it will take in dual channel, you can use the multiplier to
> make the final adjustment. Using a hacked BIOS that supports
> Command Rate 2T timing (CPC off), will allow 200MHz to be reached,
> but at the expense of reduced memory bandwidth. Of all the techniques
> I know of, all of the fixes result in reduced memory bandwidth,
> so the LL RAM is the only brute force approach that works well.
> I cannot provide a sound technical argument for why LL RAM is
> making a difference, as the interface is synchronous, and CAS2
> versus CAS3 should be a totally internal issue for the RAM, not
> affecting interface timing.
>
> Paul
Thanks Paul, I don't know what added demands dual channel RAM makes to a
system - I initially speculated it wouldn't make any at all but was
obviously wrong. I suspect running 2T & dual channel would be virtually the
same as I'm getting now. The hacked bios is the 1T command version, as is
the standard unmodded one. I am also very relieved that I can now reach
200MHz.
I can hardly complain with the current rock solid stability I'm getting with
the added grunt. Now I've gone with 1GB RAM @ 200MHz, the performance over &
above my previous XP1800+ has been worth while as a swansong to the 32bit
Athlon.
I had a further play by setting the FSB to 210 & upping the Vcore to 1.8V (3
4 4 9) but the added performance was virtually zero as measured with Sandra,
so have returned to 200MHz & 1.75 Vcore but with the Zalman fan turned up to
2220rpm (6000Cu not 7000Cu as I wrote originally) with ACPI S3 mode
restored. Quite why setting anything but optimal under System Performance
kills S3, I can't say but suspect a Bios bug unless this problem is unique
to me which I doubt. This upgrade is almost complete having recently bought
a XFX GF5200 which leaves a quieter PSU for the near future.
--
Thank people in advance? Thanking or cursing them afterwards at least gives
some feedback!
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