George said:
Hi there,
I was messing about with a usb hard disk connection which I finally
got working, but then I started getting an automatic restart cycle. In
Safe Mode I disabled the auto start and could read the blue screen.
it said DRIVER_IRQL_NOT_LESS_OR_EQUAL
THE STOP WAS 0X000000D1 (0X00000000, 0X00000002) 0X00000000,
0X00000000
I also noticed a line under those where it found two hard disks and a
dvd and a cd drive immediately after switch on. It says: serial
presence detect (SPD) device data missing or inconclusive.
Has anyone got any ideas of what is wrong and what I can do about it?
I have gone back two restore points and uninstalled the usb disk
application. I also disabled the cd and dvd drives in setup.
Help. Thanks George.
I'll just comment on the "SPD" part of your question.
*******
The computer has a low speed serial bus, which connects a few components
together. Using an Intel reference schematic for one of their older
motherboards, the primary devices on that bus are the DIMMs and the
clock generator chip.
A modern DIMM has a SPD (serial presence detect) chip on it. It is a
tiny flash memory chip, with a serial interface. The computer probes
each DIMM slot, and based on the data in the SPD, the BIOS prepares
the memory map.
The clock generator chip also has a serial interface. The BIOS can
go into the clock generator, via that bus, and turn off clocks
that are not needed (PCI bus clock, delivered per slot). Or, the BIOS
can change the primary operating frequency (which is how overclocking is done).
If you eventually get your computer running again, you can use CPUZ.
http://www.cpuid.com/cpuz.php
In the CPUZ "About" tab, is an option to "Save Report". In the
report, normally you would see a SPD table dumped in there, for
each DIMM. This is the table for one of my DIMMs (DDR2).
Memory SPD
-------------------------------------------------------------------------
DIMM # 1
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00 80 08 08 0E 0A 61 40 00 05 30 45 00 82 08 00 00
10 0C 04 38 01 02 00 03 3D 50 50 60 3C 1E 3C 2D 80
20 20 27 10 17 3C 1E 1E 00 00 3C 69 80 18 22 00 00
30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 12 72
40 7F 98 00 00 00 00 00 00 04 39 39 43 35 33 31 36
50 2D 30 31 39 2E 41 30 30 4C 46 00 00 00 08 25 A9
60 1A 20 86 00 00 00 00 00 00 00 00 00 00 00 00 00
70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
F0 39 39 43 35 33 31 36 2D 30 31 39 2E 41 30 30 4C
That shows the 256 bytes contained in the small flash memory chip
on the DIMM. If your motherboard is able to read that normally,
then that means the SMBUS is working. If you get garbage, such as
a table with only "FF" values or "00" values, then there must be
a problem with the SMBUS.
Anyway, that is the simplest diagnostic I know of, that you can
run from Windows. Attempting to read the SPD from each of your
DIMMs, is a good way to prove the bus works. If you wanted to
actually decode the data, there are JEDEC standards for the
various generations of DRAM (DDR, DDR2, DDR3 etc), which define what
those values above mean. Some of the content above is just ASCII
text, while other bytes are codes indicating the number of rows,
columns, ranks, and banks of memory.
Paul
