Patterns of Bugs

[Steven Schveighoffer]

On Fri, 07 Jan 2011 13:47:43 -0500, Walter Bright  
<newshound2 at digitalmars.com> wrote:

> Max Samukha wrote:
>> Also, memory module connectors are incompatible starting from I believe  
>> DDR. You won't be able to stick DDR2 module into DDR slot. Actually,  
>> this applies to almost any modern PC component.
>
> I put together a new box a couple weeks ago. The memory card would fit  
> in one of 4 slots. The first one I tried it in resulted in a computer  
> that just beeped at me. No help from the manual at all, I was ready to  
> RMA the mobo back, until I had the idea of putting the card in a  
> different slot. The second one I tried worked.

That is not because the slot doesn't support the dimm, it is because many  
chipsets require you populate memory in a specific order.  Usually the  
slots are color coded (blue and black for instance) to indicate which  
slots should go together (some chipsets require pairs of dimms), they are  
usually labeled with silkscreen to indicate the order.  I think I've even  
seen silkscreened instructions on which to populate first.  It sucks that  
the manual doesn't help you.

BTW, the beep is usually an indicator of a POST code.  It's because it  
cannot access the memory, so it can't run the graphics card, the beep is  
the only way it can communicate ;)  I think (but I'm not sure) that the  
beeps convey the code, but the easiest way to figure out the code is to  
plug in a POST card.

> You're right that many things in the computer hardware are better. But  
> still, many connections to the mobo can be done wrong. For example, all  
> the pins coming from the front panel. Some of them, like the hard drive  
> LED, don't even indicate the polarity on the connector, and you have to  
> try it both ways until you figure out which one works.

Typically, those are not keyed because it's not expected for a normal user  
to be accessing those cables.  Removing the cover of a PC is like casting  
in D :)

-Steve