|Not all ram that you might think should work is compatible with using it in your particular mboard. |
It is NOT a good idea to randomly buy ram or use used ram based on limited information, such as "DDR400 PC3200".
What you are supposed to do is use the model of your brand name computer, or your mboard model if you have a generic desktop system, to look up which ram module part numbers will work in your mboard for sure. If the ram you have or that you obtained is not on any list for your model, there's is no guarantee that it will work properly in your mboard, or that it will work properly with the other modules if you have more than one.
If the ram module(s) you already have, or the ram module(s) you obtain and install, are not 100% compatible with using them in your mboard, all sorts of strange things can happen. Incompatible ram modules may work fine when they are by themselves on a mboard, but they may NOT work fine when more than one ram modules is installed.
Another common problem is for people to not have the module seated properly in it's slot. Sometimes you have to try several times before it's seated properly.
Some mboards must have the ram slots populated in a certain order when you aren't filling all the slots.
Some mboards can only use some types of modules - e.g. double sided, chips on both sides - in certain slots.
See the Owner's or User's manual, or the Service or Maintenance manual, for your brand name model, or the mboard manual if you have a generic desktop system.
You MUST remove the power to the mboard whenever you unplug or plug in ram., because the ATX mboards on all modern computers are always powered in some places including some contacts in the ram slots even when the computer is not running. On desktop computers that's as long as the power supply is receiving live AC - you must unplug the computer, or otherwise switch off AC to the computer. On laptops you must both unplug the AC adapter and remove the main battery. .
The notch(es) in the bottom of the module must line up with the bump(s) in the bottom of the slot.
If you insert a module backwards in the slot, then try to boot the computer, the backwards ram module is fried instantly, and that ram slot's circuits are fried instantly, and neither can ever work again.
"...to my horror my computer had a black screen and was beeping (about 1 beep per second)."
You may merely have not had the module properly seated.
Your Compaq bios version is probably based on a standard Award generic bios version. That's the Award beep pattern for no ram installed, or a ram connection problem. Phoenix bought out Award in 1998 or so - that may also be the same thing for mboards newer than that that are based on a Phoenix generic bios version too.
The following is info I supply frequently .....
It is easy to test for incompatible ram that has caused your mboard to fail to boot, or to test for a ram connection in the slot problem.
Make sure you have a speaker or speakers or the equivalent connected to the mboard so you can hear mboard beeps (see your mboard manual if you need to).
Remove the AC power to the case/power supply.
Remove all the ram.
Restore AC power.
Try to boot.
If nothing else is wrong, you will get no video but you will hear a pattern of beeps that indicate no ram is installed, or a ram problem.
E.g. for an Award bios or a bios based on one, that's often a beep of about a half second, silence for a half second, a beep of about a half second, silence for a half second, continuously.
If you have brand name ram, it is usually easy to look up whether it's ID string (part number) is in a list of compatible modules found by using your mboard or brand name system model number.
If the ram is generic, that may be difficult or impossible.
If your ram passes a ram test, it's working fine, even if you can't determine whether it's listed for your mboard or system model anywhere
If you do a ram test, do that AFTER having tried cleaning the contacts and making sure the ram is seated properly - otherwise any errors found may be FALSE.
If the ram is incompatible with the chipset, or on more recent computers, incompatible with the memory controller built into the cpu, it will likely FAIL a ram test - that is NOT a true indication of the ram being faulty - there is probably nothing wrong with it, and it will pass the test if installed in a mboard it is compatible with.
If you want to try a memory diagnostic utility that takes a lot less time to run a full pass than memtest86 does, this one is pretty good - Microsoft's
Windows Memory Diagnostic:
It can be toggled (press T) to do a standard or a more comprehensive set of tests - use the default 6 test one first - if it passes one pass of that, use the latter one. A few of the tests in the latter set are intentionally slower.
If you don't have a floppy drive, see the Quick Start Information at that Microsoft link for how to make a bootable CD of the Windows Memory Diagnostic (you need Windiag.iso - you don't necessarily need to use the program they mention to add it to the CD).