need some pc help

[sfmarine]

A lady dropped off a computer for me to look at....I said sure. I connect the power supply and the computer turns on automatically??? odd I didn't even connect the screen yet so I had no idea what was going on. It made a few irregular beeps and then shut off. I took the computer apart and found the hard drive was not connected....I thought "problem solved" well now it won't even boot up at all. The computer has an odd smell coming from it but the motherboard light is on so that means the MB is ok right? I'm trying to figure this out. If anyone can shine some light...let me know! thanks

[kpkelley]

Have you checked the CPU? The smell could be because the gel between the cpu and the cpu fan has worn down and is now non-existent. How old is it? Could there be wear and tear problems, like the power button being stuck?

[sfmarine]

computers probably 6 give or take. It wouldn't be the power supply right? Motherboard green light is on.

[sfmarine]

I just switched out the power supply and it's doing the same thing. Light on in front and on the mother board. This is frustrating me. I messed up by not having the person show me what was wrong with it.

[glogrono]

if you remember the maker of the computer's BIOS and remember what the beeps sounded like, you might be able to find out what's wrong by going here.
http://www.cyberwalker.com/quicktips...beepcodes.html

[sfmarine]

Turns out it's definitely the motherboard. Ran a post card reader and nothing came up.

[U4K61]

A PC performs a Power On Self Test or POST that checks the hardware before turning things over to an operating system such as Windows. POST is part of the BIOS program located on flash ROM(EEPROM). POST communicates by beeps. One beep means the PC is OK. This is what we should hear every time we turn it on

1 beep, then 3,4, or 5 beeps - mother board problems.
2 beeps, the codes will be seen on the monitor.
3 beeps, then 3,4, or 5 beeps Keyboard or video controller.
4 beeps, then 2,3, or 4 beeps means the motherboard should be replaced.
Continuous beeps - power supply problems.

Hope this helps.

Back to Hardware

[MaleManGuy]

Originally Posted by sfmarine

A lady dropped off a computer for me to look at....I said sure. I connect the power supply and the computer turns on automatically??? odd I didn't even connect the screen yet so I had no idea what was going on. It made a few irregular beeps and then shut off. I took the computer apart and found the hard drive was not connected....I thought "problem solved" well now it won't even boot up at all. The computer has an odd smell coming from it but the motherboard light is on so that means the MB is ok right? I'm trying to figure this out. If anyone can shine some light...let me know! thanks

The smell could be leaking capacitors... check them for any rupture... either on the mobo or the PSU. Try a different PSU... if it still exhibits weird issues, replace the mobo. It's unlikely you'll smell the thermal paste between the HS & CPU after all this time. I'd be prone to say motherboard but i'd check the cheaper parts first like the power supply (psu)

[U4K61]

You'r right, if there is a smell, it's often a capacitor. They can be damaged even if they are not leaking. The crosshatch on top should be flat. If it looks bulged out, it's shot.

[nycomet]

Originally Posted by Craig Ruchman

You'r right, if there is a smell, it's often a capacitor. They can be damaged even if they are not leaking. The crosshatch on top should be flat. If it looks bulged out, it's shot.

Replace it with a Flux Capacitor. Better yet, get a Mac.

[Kirsty_Mc]

If it turns on automatically, then maybe there is a short in the power on wire (this leads from the switch to the mainboard). Maybe someone (prevoius owner perhaps) has deliberately shorted this so that the computer will turn on automatically after a power failure. I've heard of it being done for computers used for CCTV recording and the like. It this case it is best to use a relay setup though.

If there is an odd smell, swap out the PSU... it's likely to be this. Some PSUs when new can give off an odour too for the first few hours... but this is an obviously new smell.

[Kirsty_Mc]

Originally Posted by nycomet

Replace it with a Flux Capacitor. Better yet, get a Mac.

A klystron relay would do better... of coarse these give off quite a bit of heat, so make sure you're case is of Adamanitine Steel

[U4K61]

Originally Posted by nycomet

Replace it with a Flux Capacitor. Better yet, get a Mac.

"Admeral, we have a serious problem. It's these Klingon Crystals. The time travel drained them". I guess that spoils my chance of ever going Back to the Future to get my Flux Capacitor.

Von Neumann Architecture - program resides in memory along with the data.
1. Memory - program and data.
2. CPU - access program and data in memory
3. I/O - data input and output

Orders of Growth, Θ
Θk - costant, run time is fixed
Θlg n, run time increases more slowaly then n, Binary search
Θn, linear
Θn lg n, when n doubles run time slightly more then doubles, Merge sort
Θn^2, Quadratic, Insertion sort
Θ2^n, Exponential,
Θn!, TSP
Intractable problems: traveling salesman(TSP)

5-tuple TM
1 - current state.
2 - current symbol being read.
3 - symbol to replace current symbol.
4 - next state to enter.
5 - direction to move tape.

Church-Turing Thesis

Von Neumann Architecture - program resides in memory along with the data.

Virtual Machines - computer defined by software rather then hardware.
Procedural Programming - a list of instructions to be executed in order, imperative language.
Object-oriented(OO) - object as units of modularity (type or class).
Script - a set of operating system commands placed in a file.

Language Syntax and Semantics - Backus-Naur Form(BNF), extended Backus-Naur Form(EBNF)
Lexical Analysis (scanning) - creates a sequence of tokens
Syntax Analysis (parsing) - builds a parse tree
Semantic Analysis (code generation) -

Scripting Languages - a set of operating commands placed in a file.

Operating Systems
Deadlock - a conflic of needs a allocations that stops all computing.
1. Mutual exclusion, resources are allocated exclusively to one process. If not, as in a shared printer, lines of output from two simultaneously executing processes get intermingled.
2. Hold and wait, if not, a long running process that prints only at the end, hogs the printer the whole time.
3. No preemption
4. Circular wait

Threads, allow multiple lines of execution withen a single process.

Scheduling]
First come first served(FCFS or FIFO), batch system, when unblocked, it goes to end of FCFS queue.
Shortest job first(SJF), minimum average turnaround and max average throughput - jobs per hour.
Shortest remaining job first(SRJF), preemptive version of SJF.
Round Robin(RR), each process is viven a share of time with CPU.