[Okta Webinar] Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

Can a computer not boot due to low power supply?

Posted on 2011-09-11
18
Medium Priority
?
355 Views
Last Modified: 2013-12-11
Hi,
I have bought (second hand) a Abit N68SV with a AMD X2 7750 processor on it. I tried to start up my system using a old 300 W power supply. The result is that I don't get anything on the monitor, when I start the computer. So I am wondering whether the problem could be with the power supply just not being strong enough to start the system. However everything seems to be ok when I start, as the CPU fan is running all the time, while powered.

Cheers.
r
0
Comment
Question by:rjorge
  • 7
  • 5
  • 3
  • +2
18 Comments
 
LVL 7

Expert Comment

by:Reece Dodds
ID: 36520226
What else are you running?  If it is just mainboard, CPU, ram... then 300W is fine.  Are you certain the power supply is known good (ie. works on a different system).  
With the X2 7750, the CPU fan should spin up full speed for a moment then slow down to the regulated speed during post. If it stays full speed when you get no pic, it indicates a M/B or PSU problem.  If you can get a system speaker attached to that M/B it will help determine any problems via the audible POST beep codes.
0
 
LVL 30

Expert Comment

by:Dr. Klahn
ID: 36520233
It's certainly possible, though if the fan is running normally a problem with the 12V is not likely.  The easiest way to find out is to use a DVM to check the actual voltages at the power supply connector on the motherboard.  This site has a pinout of the 24-pin ATX connector.

If you have a PCI POST 4 card, by all means install it and see if the system is POSTing.  If the POST 4 card is counting BIOS stages as the system is powered on, there is at least an indication that the machine is not entirely dead.
0
 
LVL 93

Expert Comment

by:nobus
ID: 36521245
you can calculate how much power you need  : http://www.antec.outervision.com/
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 93

Expert Comment

by:nobus
ID: 36521250
and did you connect the 4-pin aux CPU power cable?
0
 

Author Comment

by:rjorge
ID: 36522036
@nobus. There is no 4-pin aux CPU pin in the board that I remember. Only the 24 in power supply pin. I think.
0
 
LVL 12

Expert Comment

by:asidu
ID: 36522103
You can try to remove connection for CD/DVD drive, remove off any other device and do a test.
The intiial bios flash should be seen on the screen at least. If you cannot see the bios flash
it could be the video out put to the screen need to be checked.

Check also that your RAM is connected correctly. If you have two or  more RAM sticks remove them all off and test the machine with just one. A faulty RAM stick could also give weird results.
0
 
LVL 93

Expert Comment

by:nobus
ID: 36523062
did you calculate the needed power yet?
0
 

Author Comment

by:rjorge
ID: 36525228
@all
I've calculated the load. With the CPU+2Gb DDR2+SATA HD+ATI RADEON 5670 the calculation is 219w recommended wattage. I've even tried using it without the graphics card and it still doesn't boot.So indeed the 300w should be enough.
0
 
LVL 7

Expert Comment

by:Reece Dodds
ID: 36526478
are you sure you have the 4-pin +12v connector plugged in?

have you tested the PSU on another system or tested another PSU on this mainboard?

Are you doing all your testing with the mainboard outside of a PC chassis?  As to ensure nothing is shorting out.
0
 
LVL 93

Expert Comment

by:nobus
ID: 36527537
Are you sure the PS is OK?  test it on another system to be sure, or test with a KNOWN good one
>>  I've even tried using it without the graphics card   <<  difficult to see if it boots..
if you have a V-meter, you can check +5V and +12V on molex connectors

0
 

Author Comment

by:rjorge
ID: 36527663
@all
I have noticed that I only had the main 24 pin PS cable connected. So there was a problem. The board has a 4 PIN ATX 12V slot but the PS only has a 2 PIN cable that fits in half the slots. Can that be the cause?
I've tested the PS on a older system, with a M811 motherboard and a Athlon 3000+ CPU. The system booted well, got image on the screen, although once or twice did not boot well due to the awkward position of the graphics card hanging in the air.
I've performed the tested with the MB on top of a bubble wrap, using my case's board connectors. The board was also out of the case.
0
 
LVL 12

Assisted Solution

by:asidu
asidu earned 664 total points
ID: 36527841
>>4 PIN ATX 12V slot but the PS only has a 2 PIN cable that fits in half the slots. <<
You should get the right power supply connector.

You tested your PS okie with another system not the same one in question.
So what you reckon is correct.
0
 
LVL 93

Accepted Solution

by:
nobus earned 668 total points
ID: 36528630
you should have all 4 connected
you can use an adapter cable for that :  http://www.performance-pcs.com/catalog/index.php?main_page=product_info&products_id=196
or here :  http://www.ncix.com/products/?sku=15986
0
 

Author Comment

by:rjorge
ID: 36533062
Hi all,
a small correction. The connector on the board is a 8 PIN, but the cable I had is just 4 pin. Still, I think what nobus said applies. I'll get teh adapter cable and if that doesn't work will simply change the PS.
0
 
LVL 7

Assisted Solution

by:Reece Dodds
Reece Dodds earned 668 total points
ID: 36534226
I should've googled a pic of the mainboard before I commented... the 8-pin +12v connector is used for high end CPU's and overclocked rigs.  You will be fine to use the 4-pin molex and 24-pin molexes that standard PSU's have!
There is onboard video so you don't need an expansion graphics card.

So, have the mainboard out of the chassis.  

Reset the CMOS - use the CMOS RST headers on the mainboard, or, take out the battery, short the two metal parts of the battery socket together for 5 secs, put the battery back in.

Connect just the CPU, RAM (only 1 module) and PSU (which you've already tested OK on another rig and said is working ok)...

There is no system speaker on the mainboard so raid one from another PC temporarily.

Use a screw driver to short the two pins of the on/off header (where you normally plug in the power switch - on this board it is the RED ones) of the mainboard and if the mainboard is not faulty, you should have lift off!

If all you get is a spinning CPU fan and no picture, you have a dead mainboard, bad cpu (unlikely), or faulty RAM.  If you have a system speaker attached, an audible long beep will tell you if the ram is not detected properly.

A new PSU is only what, $50, so no biggy, but buying one is a waste of time if the mainboard is faulty.
0
 
LVL 93

Expert Comment

by:nobus
ID: 36534322
here you have one 8-pin :  http://www.directron.com/ad202.html
0
 

Author Comment

by:rjorge
ID: 36569742
Final outcome. I've tested with a newer power supply and the MB did not boot. It was crooked.
0
 
LVL 93

Expert Comment

by:nobus
ID: 36571907
tx for feedback
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

So, if your PC is old or new and it does not boot or has no display then what do you do? Precautions : -During connecting or disconnecting devices, be sure to have the AC electrical power disconnected -Temporarily ground yourself, or use a wris…
Or at least that’s the word according to a new blog from Tech Target on AWS’s new Managed Services (MS) offering. According to the blog, AWS is launching their AWS MS program to expedite the adoption of cloud by Fortune 1000 and Global 2000 companie…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an anti-spam), the admin…
As many of you are aware about Scanpst.exe utility which is owned by Microsoft itself to repair inaccessible or damaged PST files, but the question is do you really think Scanpst.exe is capable to repair all sorts of PST related corruption issues?
Suggested Courses

872 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question