System wont shut down - fans remain on and lights flash...and there is a nasty sound!

[jaarus]

Hoping someone here can sort out my PC, as I am totally lost for ideas!

My PC (specs below – if you need to know anything else please ask) was all working fine then without warning it started acting strangely.

When you shut it down it turns off – BUT – the case fans keep spinning and something inside make a strange noise (kind of a mechanical tapping noise…like a CHU CHU CHU noise lol) which I think I located to the CDRW….and would just sit like that the only way to actually turn it off was to physically switch it all off at the wall.
This happened for a few days – searched the net but hard to find a solution as my description is a little too vague for Google!

Then finally nothing. The system died.

So I replaced the power supply with a better version – thinking perhaps in hindsight I had been putting too high a demand on the crappy standard PSU. And when I removed it I am sure I was!…it comes with a 150w PSU???!!

Ok so its working again – but it is still doing that odd ‘flashing’ thing when you shut down.

I then notice that NONE of my USB ports can identify any devices? – Yet they all have charge/power as I have moved my Razer Copperhead mouse (USB) and a USB cathode light around all the ports and they both light up.
I also noticed that on-board sound had gone.

(Exactly when these went I am not sure as when the flashing first started, I began my quest for answers online and I know the mouse worked then, not sure about sound though)

So I have popped an old Sound card into a spare PCI slot and a mouse made in the Neolithic period and all good – we have sound again.

I am considering buying a PCI to USB to get some USB functionality back (so I can get back to a decent mouse), but before I do…
Does anyone know what this flashing malarkey is about?

If the Mobo has taken significant damage then I am basically flogging a dead horse and may as well replace with a new base unit but that is a cost I don’t really want to fork out lol!



My system specs:
Model - Emachines 620
Windows XP (SP2)
PSU - Was 150w PSU (now replaced with a Jeantech 300w)
GFX – GeForce 6600GT AGP
RAM – 1gig DDR

Found this on Emachineupgraders.info about the mother board which is

TriGem Alaska3 Mainboard
Documented General Info:

Processor
Intel® Pentium® 4 processor400 MHz system bus with an integrated 256K L2 cache

Chipset
Intel® 82845GL Graphics Memory Controller Hub (GMCH)Processor/Host bus support Integrated DRAM controller Integrated graphics AC ‘97 controller Integrated 3D/2D graphics accelerator Integrated 350 MHz RAMDAC Arithmetic stretch blitter video Power management functionsIntel® 82801DB I/O Controller Hub (ICH4)Support for the PCI interface Integrated IDE controller USB 2.0 and DMA controller Power management logic Real-time clock Support for AC ‘97 audio devicesIntel® 82802AB Firmware Hub (FWH)Firmware Hub (FWH) interface

Memory
The motherboard has two dual inline memory module (DIMM) sockets. You can increase the amount of memory in your computer up to a possible 2 GB. Each DIMM socket supports the following memory features:184-pin 2.5 V DIMM with gold-plated contacts200/266 MHz Non-ECC unbuffered DDR SDRAM Single or double sided DIMM in the following sizes:
DIMM size Non-ECC configuration
64MB 8Mbit x 64
128MB 16Mbit x 64
256MB 32Mbit x 64
512MB 64Mbit x 64
1GB 128Mbit x 64

Audio
Integrated Audio Controller in Intel® 82801DB I/O Controller Hub (ICH4) AC '97 2.2 Compliant AC '97 Link for Audio CODEC Separate Independent PCI Function for Audio AD 1981A Audio Codec ‘97 AC '97 2.2 compatible Industry Leading Mixed Signal Technology 16-bit stereo full-duplex Codec with independent and variable sampling rate Four analog line-level stereo inputs for connection from LINE IN, CD, VIDEOand AUX Advanced power management

Video
Intel® 82845GL Graphics Memory Controller Hub (GMCH).NOTEThe internal graphics device on Intel 82845GL supports Intel Dynamic Video Memory Technology (D.V.M.T). D.V.M.T. dynamically responds to application requirements by allocating the proper amount of display and texturing memory. As your system has sharing memory architecture using the main memory for video memory, the usable main memory size is less than real size when the computer is running.

Onboard I/O Connectors
SMSC LPC47M192 Super I/O ControllerFloppy drive interface One multimode parallel port FIFO serial port Keyboard and mouse controller

Onboard IDE
N/A

Expansion Slots
3 PCI Slots

BIOS
Phoenix BIOS Plug and Play compatible Advanced Power Management (APM) and Advanced Configuration Power Interface (ACPI)

Onboard LAN
Realtek RTL8100B LAN controller-Integrated Fast Ethernet MAC, physical chip and transceiver in one chip -Supports 10Mbps and 100Mbps N-way Auto-negotiation operation -Supports 32-bit bus master data transfer -Supports wake up LAN function

IEEE 1394
• N/A

Form Factor
microATX

[Elbatrop1]

It kinda sounds like your mobo is toast.

I would reinstall Windows to make sure that it isn't software related at all. Then, if your problems still persists, swap out the mobo.

Your motherboard is a skt478. 478s now are quite inexpensive to replace, yet still somewhat readily available.

All of your current parts would work with the new mobo.

The only problem that I can forsee is if what kind of Windows install CD you have. If it is just a recovery CD, then you wont be able to reinstall Windows completely (which you need to do with a new mobo).

[sPlAtOiD]

First try to unplug the cdrw drive and try it and do you have a disk in there. If so it could be trying access it and that is hanging everything up. Its worth a try .