PSU fault and subsequent boot problems

  Catastrophe 13:43 10 May 08

1. Old system irrelevant except that it had woefully inadequate PSU (250W). Trouble developed with boot recycling i.e., would boot past Intel screen and then start all over and keep doing so.

2. Virtually stripped PC, putting in new m/b, Pentium 4 and fan and new Enermax 535W PSU (not RAM yet). On switching on there was a flash in the PSU and loud noise. I put back the old PSU and switched on - all OK so far.

3. Added HDD and DVD and tried to load XP. Booted from DVD and went through full file loading etc. but when it tried to boot from HDD it failed - apparently could not recognize HDD. Tried two good HDDs from other PCs with same result.

What I am trying to get at is:

Has the flash possibly done some damage? I am looking at the m/b and processor apparently working fine.

Is it possible that the old PSU is 'recycling' on attempted re-boot causing error suggesting HDD not there (not powered?). This ties in with former recycling behaviour but then why does it boot from CD and go through full procedure prior to re-boot? Am I missing something?

Old AOpen AX3S was replaced with Intel D865GBF.
Processor 2.40Ghz Intel Pentium 4.

I did notice that on another D865GBF m/b PC the second power cable has 2 black and 2 yellow cables. On the Enermax the same four socket connector has red, orange, yellow and black cables. The Enermax has only the plug mentioned but it has two sets of 3 black and 3 white connectors i.e., six cables instead of four.

Any suggestions gratefully received.

Thanks in advance.

  Technotiger 14:19 10 May 08

I am not an expert, but did you check that your old mobo would take your new CPU?

  Catastrophe 14:54 10 May 08

Technotiger. Thanks for your response.

No, I didn't check. I thought they were all pretty much the same except for newer additions like SATA power.

  Ditch999 15:02 10 May 08

When you get to the POST screen is the HDD detected and named in the list. If not you might have to go in to the BIOS and force it to detect it. Did you reformat the HDD before installing XP? The bang from the new PSU would indicate a short somewhere - check the mobo is not touching the case and all power leads are in correctly. There are different versions of PSUs, the term is ATX specification and should be on a label on the PSU.

  Catastrophe 15:26 10 May 08

Ditch999. Thank you for your response.

I checked regularly in the BIOS and sometimes the HDD was not listed. I have changed the cable and the PC booted from CD and proceeded to load XP so all seems solved.

Assuming all boots correctly I will marked as resolved. Thanks to all for responding. It does suggest that a short does not necessarily cause damage which is good to know (Fingers Crossed).

  Catastrophe 17:30 10 May 08

OK all's well.

But I would like some info on the second (four cable) power unit please.

  woodchip 18:50 10 May 08

Other Hard Drives from other computers will not work, The problem you have is either corrupt startup files or a Driver Problem

Technotiger PSU not CPU

  woodchip 18:51 10 May 08

Other Hard Drives from other computers will not work, The problem you have is either corrupt startup files or a Driver Problem

Technotiger PSU not CPU

Sorry just read that he as also changed cpu

  Ditch999 19:32 10 May 08

Re your 2nd Enermax PSU. This is a more powerful PSU and as such it can supply power to more components. I think it has 2 separate 12v rails which is better than your old one which probably only has one. As such there are more connectors available to use (but you do not need them all, depending on your motherboard) and the colour of the wires does not matter as connectors have a specified standard which must be followed, in other words the voltages in the wires cannot be changed around. The connectors are also predefined and you cannot (although sometimes I wonder) put the wrong plug into a motherboard or HDD or CD drive connector.

  Catastrophe 01:35 11 May 08

Ditch999. Thank you for that information.

The 4 cable power connector can be put in the wrong way (but I did not). It has two round and two square 'holes' but the m/b is marked with voltage to identify red and orange (at least I think so). It does fit more easily one way rather than the other.

  Catastrophe 02:06 11 May 08

There is something really weird going on here. From the above it is evident that the PC was working and loaded XP. BUT the front switch was not connected. I have another PC with the same m/b where the front switch has to be connected.

Having loaded XP and all working satisfactorily I powered down (front switch still not connected). Now it will not power up. It lights up momentarily and then goes out. Just as if it is waiting for the front switch to be activated. But of course it still is not connected.

Any ideas please?

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