Greetings,
I have a custom built pc (AMD Athlon 64 and Seagate 300 HD) and just started having trouble.  It just stopped powering up.  So I put in an extra power supply I had laying around and it now starts up but it beeps every couple of seconds and nothing initiates.  I know everything was hooked up right so I am stumped as to what's making it beep.  I thought maybe the memory was bad, but I don't want to just start throwning $$ at it and not know what is wrong.  PLEASE HELP!?!?!?It could be just about anything. Video card, motherboard, memory, Maybe if we knew what brand and model the motherboard, display card, etc are, we could start to guess. Do the beeps happen about 2 seconds apart? Is there a little burst of beeps at power on (if so, give number and whether long/short) and then just a regular set of beeps from then on? Are you still in touch with the custom builder?

Do you have a spare video card you could try? Maybe you could borrow some RAM? Is this a new build that has never worked right or has it been OK for a while? Did it do anything odd before it started playing up?
Thanks.  I built it so there's no one I can go to.  The motherboard is an ECS C51GM-M.  The hard drive is a Maxtor ultra 300gb, not a Seagate as I said before.  The video card is an HT2000 GeForce 6100 and came with the motherboard.  I don't have a way to borrow RAM.  The beeps are 4 seconds apart and last for 2 seconds.  They start a few seconds after the unit is powered up then continue.  The monitor shown nothing when the unit is powered up. 

I built it about a year ago and it has worked fine until last week.  Then last week it wouldn't power up at all, then I changed out the power supply and it now starts but I all I get are just beeps.   I had a simular problem once that required me to research POST errors or beeps and what there trying to indicate, therin usualy is the problem. Here is a copy of one part of the page and info to look it up for yourself...Also I agree with the prev advise..could be MEM, video, HDD or even clearing the CMOS jumper might help. If you have'nt tried that already..This is for Pheniox, AMI or Award BIOS Chips. Yours should be one of those..Beep CODES and their meanings + Website...

WebSite; http://www.amptron.com/html/bios.beepcodes.html

BEEP CODE  MEANING  POSSIBLE CAUSE 
 1 Beep (No video)  Memory refresh failure  Bad memory
 2 Beeps   Memory parity error  Bad memory
 3 Beeps   Base 64K mem failure  Bad memory
 4 Beeps   Timer not operational  Bad motherboard
 5 Beeps  Processor error  Bad processor
 6 Beeps   8042 Gate A20 failure  Bad CPU or Motherboard
 7 Beeps  Processor exception   Bad processor
 8 Beeps  Video memory error  Bad video card or memory
 9 Beeps  ROM checksum error  Bad BIOS 
10 Beeps  CMOS checksum error  Bad motherboard
11 Beeps  Cache memory bad  Bad CPU or motherboard

Award BIOS Beep Codes
Award BIOS uses beeps of varying duration. A long beep will typically last for 2 seconds while a short beep will last only 1 second. Award BIOS also uses beeps of different frequency to indicate critical errors. If an Award BIOS detects that the CPU is overheating it may play a high pitched repeating beep while the computer is running.
 
BEEP CODE  MEANING  POSSIBLE CAUSE
 1 Long, 2 Short  Video adapter failure  Bad video adapter
 Repeating (Endless loop)  Memory error  Bad memory or bad connection
 1 Long, 3 Short  Video adapter failure  Bad video adapter or memory
 High freq. beeps (while running)  CPU is overheating  CPU fan failure
 Repeating High, Low beeps  CPU failure  Bad processor
   
Phoenix BIOS Beep Codes
Phoenix BIOS uses beep code patterns to indicate problems. In the table below the '-' indicates a brief pause between beeps.
Example: 1 - 1 - 2  would sound like BEEP BEEP BEEP BEEP
 
 BEEP CODE  MEANING  POSSIBLE CAUSE
 1 - 1 - 2   CPU / motherboard failure  Bad CPU / motherboard 
 1 - 1 - 3  CMOS read/write failure  Bad motherboard
 1 - 1 - 4  BIOS ROM failure  Bad BIOS chip
 1 - 2 - 1   Timer failure  Bad motherboard
 1 - 2 - 2  DMA failure  Bad motherboard
 1 - 2 - 3  DMA failure  Bad motherboard
 1 - 3 - 1   Memory refresh failure  Bad memory
 1 - 3 - 2  64K memory failure  Bad memory
 1 - 3 - 3  64K memory failure  Bad memory
 1 - 3 - 4  64K memory failure  Bad memory
 1 - 4 - 1  Address line failure  Bad memory
 1 - 4 - 2  Parity error  Bad memory
 1 - 4 - 3  Timer failure  Bad motherboard
 1 - 4 - 4  NMI port failure  Bad motherboard
 2 - 1 - 1  64K memory failure  Bad memory
 2 - 1 - 2  64K memory failure  Bad memory
 2 - 1 - 3  64K memory failure  Bad memory
 2 - 1 - 4  64K memory failure  Bad memory
 2 - 2 - 1  64K memory failure  Bad memory
 2 - 2 - 2  64K memory failure  Bad memory
 2 - 2 - 3  64K memory failure  Bad memory
 2 - 2 - 4  64K memory failure  Bad memory
 2 - 3 - 1  64K memory failure  Bad memory
 2 - 3 - 2  64K memory failure  Bad memory
 2 - 3 - 3  64K memory failure  Bad memory
 2 - 3 - 4  64K memory failure  Bad memory
 2 - 4 - 1  64K memory failure  Bad memory
 2 - 4 - 2  64K memory failure  Bad memory
 2 - 4 - 4  64K memory failure  Bad memory
 2 - 4 - 4  64K memory failure  Bad memory
 3 - 1 - 1  SLAVE DMA failure  Bad motherboard
 3 - 1 - 2  Master DMA failure  Bad motherboard
 3 - 1 - 3  Interrupt controller failure  Bad motherboard
 3 - 1 -4  Slave IC failure  Bad motherboard
 3 - 2 -2  Interrupt Controller failure  Bad motherboard
 3 - 2 - 3     
 3 - 2 - 4  Keyboard control failure  Bad motherboard
 3 - 3 - 1  CMOS batter failure  Bad CMOS battery
 3 - 3 - 2  CMOS configuration error  Incorrect setting
 3 - 3 - 3     
 3 - 3 - 4  Video memory failure  Bad video card or memory
 3 - 4 - 1  Video init failure  Bad video card or memory
 4 - 2 - 1  Timer failure  Bad motherboard
 4 - 2 - 2  CMOS shutdown failure  Bad motherboard
 4 - 2 - 3  Gate A20 failure  Bad motherboard
 4 - 2 - 4  Unexpected interrupt  Bad processor
 4 - 3 - 1  RAM test failure  Bad memory
 4 - 3 - 3  Timer failure  Bad motherboard
 4 - 3 - 4  RTC failure  Bad motherboard 
 4 - 4 - 1  Serial port failure  Bad motherboard
 4 - 4 - 2  Parallel port failure  Bad motherboard
 4 - 4 - 3  Coprocessor failure  Bad motherboard or CPU.
 9 - 2 - 1  Video adapter incompatibility  Use a different brand of video card
 
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Thanks!  Based on that info I would have to guess it's the memory.  I will take one 1GB of RAM from the pc I built and have at my office and try using that in the one at home that is beeping.  Then if that doesn't fix it I will move to the next possibility.There's a chance the other PSU isn't up to snuff either...borrow a known good one of the same or greater wattage and test it for 24 hours to see...