Except there was not a bios flash...


"Mikey" mused:

:Hi;
:After the bios flash. your front side bus reverted to a safe setting lower than 200: either 133
:or 166 so your DDR memory (2 x FSB) became DDR266 or 333)== acceptable for any of your sticks
:at CL2.
:It always revert to a SAFE SETTING and you have to adjust the FSB to the CPU's or end up w.
:lower perf.
:
:
:"Paul" wrote in message ...
: In article , Howie
: wrote:
:
: A7N8X-Deluxe board running 3 sticks of 256mb Infineon PC3200 DDR400
: RAM CL2.5...
:
: I swapped one of the sticks at my local computer shop for one stick of
: Samsung PC3200 CL3 512mb. The logic was twofold: 1) Wanted to
: increase system RAM to 1gig and 2) Take advantage of the Dual Channel
: capability of this board (256+256 in slots 1 & 2, 512 in slot 3).
:
: Got home, installed the 512mb stick, everything booted up fine, 1gig
: of RAM in place. I then ran Sandra to analyze the memory and it
: reported the new stick was CL2.5 up to 166MHz and CL3 up to 200MHz.
: While I didn't feel this was anything to be concerned about in the
: grand scheme of things, I did take note of the fact my 256mb sticks
: were rated at CL2.5 at 200MHz and the new 512mb stick CL3.
:
: Then, quite ignorantly, I decided to play a bit with the memory
: settings. I selected "Aggressive" from the BIOS, saved, and received
: an audible report the "System Failed Memory Test". I quickly realized
: I could not simply reboot and get into the BIOS to change this setting
: back, so I removed the new stick of memory, leaving the two 256mb
: sticks in Slots 1 & 2. I was somewhat surprised to receive the same
: error warning, so I removed the stick from Slot 2, tried again, and no
: dice.
:
: Before resorting to flashing a new BIOS, on a whim I removed the
: remaining 256mb stick and replaced it with the 512mb stick-- Slot 1.
: I say "a whim" as it was rated at CL3 and I recall the "Aggressive"
: settings being in the neighborhood of CL2.5 in the BIOS memory setting
: menu.
:
: I was shocked to hear the computer POST and I was able to get into the
: BIOS, change the setting, reinstall the 1gig of memory, and proceed as
: if nothing happened. I considered myself lucky as I didn't really
: feel like fooling with a reflash!
:
: Anyway, a couple of questions that I have from that episode...
:
: 1) Does it make sense that with the "Aggressive" settings, my machine
: would boot with memory rated "slower" (rated CL3 memory installed
: allowed it to boot where rated CL2.5 failed)?
:
: 2) Does the possible answer lie in the logic that my CL3 rated Samsung
: memory is faster than advertised and the CL2.5 rated Infineon memory
: is perhaps "overrated"?
:
: 3) I believe, dual channel or otherwise, my system will default to the
: slowest rated RAM (CL3). Is this correct?
:
: 4) Even with CL2.5 rated RAM, if the BIOS memory settings call for
: CL3, I presume the memory will "throttle back" to the CL3 speed (it
: appears the "Auto" setting calls for this CL3 speed)?
:
: 5) It has been suggested in this group that the benefits of
: dual-channel capability are miniscule, at best, versus single channel.
: What discernable performance difference will one find with memory
: running at CL2.5 versus CL3? I should have asked this question prior
: to fiddling with the setting as it might be one of those imperceptible
: gains noticeable only on benchmark testing.
:
: Thanks in advance for your answers, input, and counsel!
:
: --Howie
:
: 1) On some boards, the more aggressive memory settings (like "Turbo")
: select a CAS2 setting. There are now a couple of memory supplies who
: have silicon that is likely to do CAS2, no matter how it is binned.
: The latest revision of Samsung TCCD and the Micron chips used in
: Ballistix are examples, and between them, there are seven brands
: of CAS2 memory using those chips. If the same chips are used to
: make ordinary DIMMs, there is a good chance they too will run at
: enhanced timings.
: 2) You are possibly looking at different generations of silicon dice,
: so the answer is yes.
: 3) Yes, the slowest DIMM determines the timings used.
: 4) Yes. The CAS value is actually written into the DRAM chip at POST,
: as part of the DRAM initialization. There is a register in the chip,
: where the CAS value is written. If the BIOS writes too aggressive a
: value into the DIMM, then obviously the machine will crash big time.
: Selecting "turbo" would do that. When "By SPD" is used, the BIOS
: reads the acceptable timing from the SPD chip on the DIMM, to figure
: out what CAS value to write into the DDR memory chips. This special
: write operation is required, as the DDR chips and the Northbridge
: have to agree on the delay to expect, before data will be delivered.
: 5) The easiest way to test the difference, is to prepare a memtest86
: boot floppy (memtest.org). It only takes a few seconds to boot
: (less than booting Windows), and puts a bandwidth number in the
: upper left corner of the screen. You can compare memory bandwidth
: numbers that way. I think you will be quite surprised by the
: answer. A second way to do it, is to get a Knoppix boot CD, which
: has a copy of memtest86 built in, and memtest86 can be run from
: the boot prompt. It too boots in a matter of seconds, and gives
: the same info. Knoppix is a large download (700MB), so it is best
: to borrow a copy from someone and burn your own. I like Knoppix,
: because you can disconnect the hard drive, and experiment with
: overclocking, without having to worry about corrupting your
: hard drive. You can download and run Prime95 (Linux version,
: from mersenne.org) while using Knoppix. Once you pass memtest and
: Prime95, then it is safe to boot Windows. You can watch the Knoppix
: boot screen, and if you see "segmentation fault", or the boot
: process freezes, those are good indications that your core
: frequency is too high.
:
: HTH,
: Paul
: