i've got exactly the same problem on a Compaq Deskpro EN 6400/6.4.
It must be a Compaq BIOS problem?
I have already noticed this qeury on linuxquestions.org, but there was not an answer to this.
I try booting Knoppix from CD on my Compaq Armada 7400 laptop, but not successful, the CD is found, SYSLINUX is started, but then boot process halts (I can see the message SYSLINUX DEBIAN 2.04 (Debian, 2003-06-06) followed by a bunch of garbage symbols). When I boot Knoppix from diskette using the same CD, the system loads without any problem. Another hint is that I can boot the system from the same CD on another laptop Compaq Evo N600c.
Appreciate every advice.
i've got exactly the same problem on a Compaq Deskpro EN 6400/6.4.
It must be a Compaq BIOS problem?
32GB DDR4-2666 SODIMM Kingston KVR26S19D8/32 Equivalent Laptop Memory RAM New
$49.99
A-Tech 8GB DDR3 1600 PC3-12800 Laptop SODIMM 204-Pin Memory RAM PC3L DDR3L 1x 8G
$13.99
Crucial DDR3L 16GB 1600 2x 8GB PC3-12800 Laptop SODIMM Memory RAM PC3 16G DDR3
$22.45
Team T-FORCE VULCAN Z 32GB (2 x 16GB) PC RAM DDR4 3200 (PC4 25600) Memory
$54.99
[ BULK LOT OF 10 ] 8GB DDR4 Desktop RAM SAMSUNG, HYNIX etc. (10x)
$89.99
8GB PC3L-12800S 1600MHz SODIMM DDR3 RAM | Grade A
$12.00
HyperX FURY DDR3 8GB 16GB 32GB 1600 MHz PC3-12800 Desktop RAM Memory DIMM 240pin
$15.90
Crucial Pro RAM 32GB Kit (2x16GB) DDR4 3200MHz CP2K16G4DFRA32A NEW
$54.99
256 GIGABYTES - LOT OF 16 LAPTOP MEMORY RAM MODULES 16GB EACH TOP BRANDS
$299.99
Dell SNPTP9W1C/16G 16 GB 2666MHz (PC4-2666) Memory Ram
$34.95