FIC 4386-VC-HD пропал L2-кеш

Древняя материнка, служившая верой и правдой больше 20 лет, внезапно перестала видеть L2-кеш.

Что делалось:
- перемычки заменены на новые и их комбинация проверена многократно;
- проверялись резисторные сборки;
- кварц заменен на новый;
- чипы кеш-памяти проверялись заменой.

В BIOS'е пункт "External cache" активен. Вот результаты проверки SpeedSys и Cachechk7:

CACHECHK V7 11/23/98 Copyright (c) 1995-98 by Ray Van Tassle. (-h for help)
CMOS reports: conv_mem= 640K, ext_mem= 7,168K, Total RAM= 7,808K
386 Clocked at 39.0 MHz
Reading from memory.
MegaByte#: --------- Memory Access Block sizes (KB)-----
1 2 4 8 16 32 64 128 256 512 1024 2048 4096 <-- KB

0: 64 63 63 63 63 63 63 63 63 63 -- -- -- us/KB
1: 64 63 63 63 63 63 63 63 63 63 63 63 63 us/KB
2 3 <--- same as above.
4: 63 63 63 63 63 63 63 63 63 63 63 63 63 us/KB
5 6 7 <--- same as above.
Extra tests----
Wrt 35 35 35 35 35 35 35 35 35 35 35 35 35<-Writing
This machine does not seem to have any cache.
Hmmm. It looks like megabyte #1 isn't being cached!
Hmmm. It looks like megabyte #2 isn't being cached!
Hmmm. It looks like megabyte #3 isn't being cached!
Hmmm. It looks like megabyte #4 isn't being cached!
Hmmm. It looks like megabyte #5 isn't being cached!
Hmmm. It looks like megabyte #6 isn't being cached!
Hmmm. It looks like megabyte #7 isn't being cached!
Hmmm. It looks like RAM at megabyte #1 is REALLY slow!
Hmmm. It looks like RAM at megabyte #2 is REALLY slow!
Hmmm. It looks like RAM at megabyte #3 is REALLY slow!
Hmmm. It looks like RAM at megabyte #4 is REALLY slow!
Hmmm. It looks like RAM at megabyte #5 is REALLY slow!
Hmmm. It looks like RAM at megabyte #6 is REALLY slow!
Hmmm. It looks like RAM at megabyte #7 is REALLY slow!
Main memory speed -- 17.4 MB/s 60.1 ns/byte (100%) [reading] 9.0 clks
Effective RAM access time (read ) is 120ns (a RAM bank is 2 bytes wide).
Effective RAM access time (write) is 67ns (a RAM bank is 2 bytes wide).
386 Clocked at 39.0 MHz. Cache ENABLED.
Options: -t0

Возможно кто-нибудь сталкивался с такими причудами?