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Help! Computer wont turn on!

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August 18, 2009 11:47:37 AM

K for starters .....help!
i bought a custom built computer off ebay about a year ago and i have been gradually upgrading it. Its come to the point now where i have upgraded every part in the computer.

Here are my system specs -

Power supply - Corsair 400w CX

Motherboard - ASUS P5QL -EM

RAM - KingMax 2gb 800mhz
Jet Max 2gb 800mhz ( original )

Primary Hard drive - WDC 160gb

Secondary Hard drive- Samsung 500gb

Graphics card - ASUS 8400gs 512mb

TV card - Leadtek DTV 1000s

Case - Thermaltake V9 black edition

DVD drive - Sony DVD RW

Heres the problem. i press the power button to turn on my computer. Nothing happens. Ive checked the wall socket, its fine, checked the jumpers on the motherboard, they are fine. This, i think could be important, if i leave my computer off for 3 hours, it will start and run fine for about 15 - 30 minutes until it randomly turns off. No ' Windows is now shutting down' it just turns off in an instant. at one time that i have got it going, i checked the temperatures for everything and it was all running normally. Anyway if it was overheating , it would run everytime i press the power button then turn off once it gets too hot. I have read in other forums that RAM could be the problem, but if it was broken RAM, then the computer would start everytime i press the power button and the bios would beep ' ram problem.'
i recently installed an old floppy drive out of an old computer, thinking that it could become useful one day. About three weeks later, my computer started having this problem. One thing i must mention though, about 2 weeks ago, it didnt start when i pressed the power button about 3 times. Then for the next week, it was fine, no problems, started everytime. But this week, it hardly starts at all. I was running the computer 24/7 for a about 6 months, probably more, um so that could be something important. But when i was running it 24/7 i had a different, Rather awful power supply. The power supply i have now is only about 2 months old, its pretty new so i dont really think that it could be the problem. another thing i should mention is that if i press the power button continuously, i can see the case fans and the CPU fan Spinning for about 2 rotations and then stopping. The fans try to get going before the hard drives have a chance to get started. Another thing that could be important is that when i get myu computer going and then it decides to randomly shut down, as the fans are winding themselves down after losing power, my front LED fan flickers its lights, really dont know why though.

K ive told you you guys pretty much everything that could be causing the problem. Please help !ive put so much money into my computer i really wont it to go again.

Thanks in advance,

chilax747

More about : computer wont turn

a b B Homebuilt system
August 18, 2009 1:07:57 PM

Since you have more or less rebuilt your computer, and probably added many more peripherals, I think you just maxed out your PSU. You didn't mention what processor you have, but just going by the other things you have in there you may have been pushing the limit.

You can test this by disconnecting power to your second HD, the floppy drive, pulling the tv card, and the extra 2 RAM modules. If your computer behaves normal again, it's definitely a weak PSU for your hardware. The other option is to just buy a new PSU that's larger anyway. 400W is really not enough unless you are building a specialized low power computer.
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a b B Homebuilt system
August 18, 2009 4:40:04 PM

wathman said:
Since you have more or less rebuilt your computer, and probably added many more peripherals, I think you just maxed out your PSU. You didn't mention what processor you have, but just going by the other things you have in there you may have been pushing the limit.

You can test this by disconnecting power to your second HD, the floppy drive, pulling the tv card, and the extra 2 RAM modules. If your computer behaves normal again, it's definitely a weak PSU for your hardware. The other option is to just buy a new PSU that's larger anyway. 400W is really not enough unless you are building a specialized low power computer.

The Corsair 400CX is a quality PSU. That computer isn't coming close to maxing it out. I would focus on the RAM first. Do the RAM have the same timings and voltage specs? Mixing different brands of RAM can cause problems. I would definitely run Memtest86+ overnight to test for RAM errors. RAM errors can cause all sorts of problems. The BIOS won't necessarily give you a beep code for faulty RAM.

I know you said the temps were "normal", but what are your idle/load CPU/GPU temps? This sounds like an overheating problem. The system may need to cool down before it will attempt to boot.
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a b B Homebuilt system
August 18, 2009 5:17:44 PM


the 400CX is a quality unit, though I still think power needs to be investigated since he started having problems after installing a floppy drive of all things. This really should not be a huge burden on the system, one calculator I found estimated an additional 5 watts draw.

I'm also interested in temps, and what ambient case temp is near the PSU. I looked closely at the specs on the 400CX and it's wattage rating is based off 40C ambient temp. Much better than the no-name crap that usually test at 25C, though even Corsair's higher PSU models were tested at 50C and above.

It might be worth while to check for any wires or points of contact causing a short on the case or on the board somewhere, I'm not sure what your experience level is on working on systems is, and since you mentioned that this is an ebay builder's computer, the build might have been rushed and something simple like a poorly fitted standoff is causing a short.

Otherwise, the RAM is still a possibility, especially the mixing of modules has me wondering.
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August 19, 2009 1:52:25 PM

shortstuff_mt said:
The Corsair 400CX is a quality PSU. That computer isn't coming close to maxing it out. I would focus on the RAM first. Do the RAM have the same timings and voltage specs? Mixing different brands of RAM can cause problems. I would definitely run Memtest86+ overnight to test for RAM errors. RAM errors can cause all sorts of problems. The BIOS won't necessarily give you a beep code for faulty RAM.

I know you said the temps were "normal", but what are your idle/load CPU/GPU temps? This sounds like an overheating problem. The system may need to cool down before it will attempt to boot.


i have found the timings and voltages for my RAM .....Gotta love CPU-z!

Slot #1:
Module Size: 2048MBytes
Max Bandwidth: PC2-6400 (400MHz)
Manufacturer: Kingmax Semiconductor
Part Number: KLDE88F-B8KB5

Timings Table:
Frequency: [200MHz][266MHz][400MHz]
CAS# Latency: [3.0][4.0][5.0]
RAS# to CAS#: [3][4][5]
RAS# to Precharge: [3][4][5]
tRAS: [9][12][18]
tRC: [12][16][23]
Voltage: [1.8][1.8][1.8]

Slot 3 #

Module size - 2048mb
Max bandwidth- PC2-6400 (400MHz)
Manufacturer- Transcend information
Part number- JM800QLU2G

Timings Table:
Frequency: [200MHz][266MHz][400MHz]
CAS# Latency: [3.0][4.0][5.0]
RAS# to CAS#: [3][4][5]
RAS# to Precharge: [3][4][5]
tRAS: [9][12][18]
tRC: [12][16][23]
Voltage: [1.8][1.8][1.8]

k so there are the timing and stuff for my RAM. im not really experienced with timing tables but im guessing that because the timing tables are identical , that the timings and voltages are the same on both sticks.

I did, however , figure out a way to test if it is the RAM causing the problem. what i did is i took the RAM out of the equation. So, i took the two sticks of RAM out of my computer and tried to start it . Normally, if a computer does not have RAM installed, the computer will start but because the BIOS relies on RAM, none of the hardware will work. Anyway, i tried to start my computer without the RAM and the problem remains. It didnt start. Pushed the start button and nothing happened.
So from that i have a question - Does my test rule RAM out as the cause?

As a response to temperatures, i took a temperature reading using speedfan and these were the results. I must mention that these readings are in celcuis. These readings were taken while the computer was idle.

GPU- 38
System- 31
CPU- 25
AUX- 26
HD0- 21
HD1- 26
Core 0- 25
Core 1- 25
Graphics core - 38

For those of you who are wondering why my graphics card is running hot compared to the rest of my system, i must tell you that my graphics card is fanless, so naturally it runs pretty hot.

I must also mention that i attempted to run MEMtest but my computer decided to shut down before memtest had a chance to properly finish. Memtest was running for about 20 minutes before my computer shut down and it did not find any faults in the 20 minutes it was running, which isnt really saying all that much.

I must also mention too that my Processor is an Intel Core 2 Duo e8400 3.0 Dual Core.



This is important.
i must stress that it seems that the longer that i leave my computer off for, the longer it stays on before shutting down by itself. This only works if the computer is unplugged from the wall . If the computer is off and remains plugged in and there is a small amount of power going to it, it does not work. This has been the only constant with my problem. The longer i keep it unplugged from the wall, the longer it will stay on before spantaneously turning off.

Help.

In your expert opinion guys, will buying a new motherboard fix my problem?

Or will buying two identical sticks of RAM solve my problem?

thanks in advance

chilax747



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Best solution

a b B Homebuilt system
August 19, 2009 3:45:27 PM

your CPU-Z memory info helps some, and I don't see any clear indication that the timings/voltages are mismatched. Having a hard time locating manufacturer specs on that Transcend module though. Can't really say if it is the root of your problem or not.

As for temps, those aren't bad at all.

Have you tried running just 1 RAM module and seeing if you still have instability? If the system works fine with 1 DIMM, try placing the second DIMM on the other channel. This will force both sticks to run in single channel mode, and it's a trick I've used in the past for a quick fix. You will lose a little performance without the dual channel, but unless you absolutely must have the extra few fps in your games, you won't notice much of a performance hit.

If these RAM changes don't help you out, I would borrow a PSU from another computer that can handle your hardware and see if that changes anything. You could even buy one from Best Buy and keep the receipt, if it still has issues with a PSU swap, return it. I'm not really convinced it's a PSU issue, but this is the surest way to know, and it's an easier fix than swapping out the motherboard. That's the last thing I would try in your case.
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August 20, 2009 10:39:09 AM

wathman said:
your CPU-Z memory info helps some, and I don't see any clear indication that the timings/voltages are mismatched. Having a hard time locating manufacturer specs on that Transcend module though. Can't really say if it is the root of your problem or not.

As for temps, those aren't bad at all.

Have you tried running just 1 RAM module and seeing if you still have instability? If the system works fine with 1 DIMM, try placing the second DIMM on the other channel. This will force both sticks to run in single channel mode, and it's a trick I've used in the past for a quick fix. You will lose a little performance without the dual channel, but unless you absolutely must have the extra few fps in your games, you won't notice much of a performance hit.

If these RAM changes don't help you out, I would borrow a PSU from another computer that can handle your hardware and see if that changes anything. You could even buy one from Best Buy and keep the receipt, if it still has issues with a PSU swap, return it. I'm not really convinced it's a PSU issue, but this is the surest way to know, and it's an easier fix than swapping out the motherboard. That's the last thing I would try in your case.


i took your advice and recovered my Old PSU from the depths of room and guess what ..... it works fine! Turns on first go everytime! I also figured out why my PSU started acting stangely. On all PSUs there is a switch on the back of them , like a 'power supply on' switch. Because of the circumstances are rather hard to explain, for the past 4 weeks i have been turning off my computer using that power supply off switch. it is my understanding that doing that made my power supply do weird things like only running after being left off for ages.

Oh well, lesson learnt. I Brought the same Corsair cx400 today and now i know to treat it nicely.

My random RAM was blamed as the cause of the problem. hence, to avoid any future problems, im going to buy some proper matched RAM sometime in the near future. Ive decided on spending around 100AUD or so on RAM. I want two 2 GB sticks of RAM running at 800mhz. But oh so many choices!(sorry hijacking the thread a bit !)

Any recomendations on 2x2 GB sticks of RAM?
Hmm... im thinking ....Corsair maybe?

Thanks for your help guys ......it helped alot and i really appeciate it .

chilax747
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a b B Homebuilt system
August 20, 2009 12:31:39 PM

Corsair i would recommend, their sticks are very stable, and they have a brilliant customer service/RMA service (talking from personal experience).
Here's a good set from UK supplier Scan.
And here is (i think) the same model from US supplier Newegg.

Just for the record chilax, PSU's run more cool and efficiently at 50% load, when you ever come to upgrading your pc again, get one considerably bigger in wattage than what you estimate your system will need. I estimate my system takes between 600 and 700w on high load and my PSU is a 1200w Xigmatek NRP and i have no issues what so ever with power (touch wood).
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a b B Homebuilt system
August 20, 2009 12:35:09 PM

Glad you got your PSU issues sorted out, that really is a weird one. Corsair has a good rep for memory, though there are plenty of fine choices out there as you mentioned. The largest problem with your current RAM was that it was "bottom of the barrel cheap" to begin with. That kind of RAM will meet minimum specs, though they do not handle high demand, heat, or variation very well. Since you are going with DDR2, there should be plenty of good RAM kits for a nice price. Things to look for: you want good memory timings. "CAS latency" is probably the most important. CAS 6 or 7 is probably the range you are looking at. memory timings sometimes come as a string of numbers like 7-7-7-7-24, CAS latency is the first number when timings are listed like that. When comparing 2 similar modules, go for the one with the lower rated voltage. 1.5v is better than 1.9v: if the timings are the same, but one kit needs 1.9v to give you stable bandwidth, the 1.5v is higher quality RAM.

Other manufacturers to consider: OCZ, Mushkin, G.Skill, Patriot, Super Talent. Also keep in mind that regardless of how good a manufacturer is, there will always be dud modules. Always buy from a place that has a good return/exchange policy.
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