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Dead mobo or cpu? How do I tell?

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October 28, 2006 3:12:24 AM

Crappy timing! I'd all but decided to wait to purchase. I get home tonight and poof, no boot. Getting the normal post beep, then nothing. Everything spins up, fans are going, etc. I CAN get to the bios. After that, just a dark screen. This rig is about 4 years old, so it's served me well.

Any way to tell if it's the cpu or mobo?

I have an Asus A7V8X and an AMD 2200+. Can replace the cpu pretty cheap, and I'm assuming I can still get a Socket A mobo out there somewhere. Just need to figure out which one it is.

Thanks for any help.

More about : dead mobo cpu

October 28, 2006 3:50:09 AM

Your motherboard and CPU are most likely just fine. The fact that you can get into the BIOS indicates this.

At this time, the suspects for the malfunction are the video card and your memory. I think the video card is a little more likely.

Try a different video card if you have one. If not see if you can borrow one from a friend for a few hours (or buy one from a local retailer and return it if it turns out that the problem isn't the video card)

HTH.
October 28, 2006 3:50:20 AM

Youmay need a new battery ( 3 or 4 bucks) for mobo, I had a similar prob before and I replaced the battery and it seemed to fix things...start with the least expensive I always say...Can you load defaults...good luck
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October 28, 2006 4:07:58 AM

Checked the vid card. Had an old MX400 laying around. Same problem. Will test the memory tomorrow. Memory is only about a year old. PC 3400 I think? DDR 400 Corsair value 512X2. I have some older memory around I can replace it with to check. Also figured I'd get the post beep errors if it were vid or memory, but who knows.

Didn't think you could get into bios if the battery was toast, but I've been wrong once or twice. Will give that a go if the rest checks out.

One other thing, the hard drive light never comes on, but I think it's just because it's not getting that far in the boot process.

Thanks again, and keep any suggestions coming.
October 28, 2006 4:29:07 AM

Since you have two sticks of memory, you can try them one at a time.

There is always a possibility that they are both bad but that would be really unusual. Attempting to boot your PC with each stick one at a time should tell you if one of them isn't working properly anymore.

HTH
October 28, 2006 5:36:27 AM

Quote:
One other thing, the hard drive light never comes on, but I think it's just because it's not getting that far in the boot process.


Well, ruling out the hard drive is certainly another next good thing to do. Try unplugging the power from the hard drive and booting windows (or anything else, for that matter) from CD (or diskette).

I assume you've already tried pulling out all PCI cards just to rule those out too, correct?

-john, the ambivalent dinosaur
a b V Motherboard
October 28, 2006 10:40:15 AM

Quote:
Checked the vid card. Had an old MX400 laying around. Same problem. Will test the memory tomorrow. Memory is only about a year old. PC 3400 I think? DDR 400 Corsair value 512X2. I have some older memory around I can replace it with to check. Also figured I'd get the post beep errors if it were vid or memory, but who knows.

Didn't think you could get into bios if the battery was toast, but I've been wrong once or twice. Will give that a go if the rest checks out.

One other thing, the hard drive light never comes on, but I think it's just because it's not getting that far in the boot process.

Thanks again, and keep any suggestions coming.
Your videocard works, cpu and memory also pass POST.
The battery on your mobo holds BIOS settings, date and time info.
If dead BIOS goes to default when you turn on the power, but once powered up the system does not use battery power. I think you should replace it.
After a successful POST you should see either:
a) a succesful OS boot, or
b) a request by the system for a boot device. Do you see this?

No lights on the hard drive are an omen. The HDD should have already powered up and be ready for the boot request. Since you can get into the BIOS setup, does it recognize the HDD in your system?
October 28, 2006 2:22:15 PM

Quote:
The battery on your mobo holds BIOS settings, date and time info.

The date and time are correct when I get into the bios, so it seems it's retaining the info. May be able to rule out a dead battery.
Quote:
b) a request by the system for a boot device. Do you see this?

Nope. Just a dark screen.
Quote:
Since you can get into the BIOS setup, does it recognize the HDD in your system?

Will have to look a little closer at this tonight. I went through the bios settings, set everything back to default, I'm pretty sure I remember seeing the HDD there, but will verify. It doesn't even start the boot sequence. I have it set in the bios to boot from hard drive 1st, since I don't keep a floppy installed. Will see if I can boot from my Windows 2000 cd tonight. Normally when a hard drive dies, you get some sort of an error that it can't find the device, etc. As I mentioned, the boot sequence never begins. Immediately after I exit the bios, there's nothing. Normally you get the pc going through it's motions recognizing devices, but this never happens.

Only other pci cards installed are my network card (on board nic died) and my sound card. Neither of which should keep it from booting, but I'll pull them just to verify.

I have a couple of old pc's with some spare parts in the closet. An extra hard drive that I can't even format anymore, but I can at least install it to see if it's recognized. My wife has an old e-machine, I'll yank her HDD for testing if I need to as well. I have extra cables, memory, etc. Thanks for the input so far. Unfortunately I'm at work till 8 tonight, so it'll be a while before I can provide any additional info.
October 28, 2006 3:05:34 PM

ok speaking about your BIOS...It's a good place to see everything. I haven't read every single post on this topic, but I remember seeing something earlier about checking your RAM. Does all of your RAM appear in the BIOS? I have had a problem like this before where a stick of RAM went bad and my BIOS, in turn, only recognized half of the RAM I had installed...

CT
October 29, 2006 3:22:50 PM

OK, here's the latest. Everything is being recognized in the bios. Pulled my hard drive, and plugged in an old one. No change. Plugged my old hard drive back in, and now not even getting a post beep. Nothing at all. Pulled everything except for cpu off of board. Reinstalled piece by piece. Still nothing. I was getting power to my CD drive previously, and could power off from front power button. Not any more. Only way is by flipping off the power supply in the back. I've check every power cable I can think of. The fron t power LED was working before as well, but now never comes on. Power light on mobo is on however.
October 29, 2006 4:53:10 PM

Well, even after 2 (ok, 3) cups of coffee I still can't tell from the above if the problem is the PSU or on the mobo. All I can think to suggest is, if you haven't already, try swapping a known good PSU unit if you can. Test this again with a threadbare config i.e. only CPU, 1 stick RAM, and video.

Theoretically you could also swap the PSU from the failing system into a known good system, but it's not something I'd recommend since if the PSU is bad it might just destroy the mobo of the other system. Destroying a good mobo is not a cost-efficient way to test a PSU.

You wouldn't happen to have a digital multimeter (voltmeter) around you could use to sanity check what the PSU is supplying to the mobo, would you?

-john
I seem to suffer from some sort of conservation of knowledge law. The more I post, the less informational content in the post.
October 29, 2006 5:01:22 PM

Quote:
You wouldn't happen to have a digital multimeter (voltmeter) around you could use to sanity check what the PSU is supplying to the mobo, would you?

Unfortunately, no. I have an older psu I can plug in to check it. Will be a bit before I can get to it, but will report back. Thanks.
October 29, 2006 7:44:44 PM

It's not the PSU, but I think I may have traced it back to the mobo. This is a bit odd. I can hear the HDD spin up with power connected, but only if the IDE cable is not attached to the mobo. Same with the CD drive. I can get power to the CD, but only if the cable isn't attached to the mobo. I've tried a couple of different cables on both the HDD and CD, but with the same result. Still can't get to the bios anymore, so I don't know what that means now. So ya'll think it's pretty safe to assume it's the mobo that's gone bad?
October 29, 2006 8:24:14 PM

Just a thought for if you do decide to replace the mobo/cpu (which looks likely now). You might want to move to a new mobo/cpu, a newegg Athlon socket 754 or 939 combo, for example, rather than trying to replace your socket A system.

The cost difference might not be that much and you should be able to take your existing DDR RAM forward to a newer AMD socket/CPU. Wouldn't be optimal, of course, but it would probably work and still be faster than what you had, no?

Not sure there's any real truth in what I just said above. But figured it was worth mentioning in case you wanted to run some numbers and see how things looked in the context of your family budget.

FWIW, -john
October 29, 2006 8:42:05 PM

Replacing the whole rig in Feb. Replacing what absolutely must be replaced now. Looking like it's the mobo, guess I'll cross my fingers. :lol: 
October 29, 2006 9:32:47 PM

clear cmos?
try booting with just the hard drive?
October 30, 2006 3:05:19 AM

Cleaing the cmos is probably the ONLY thing I haven't tried. Will try it in the morning. It's late, and the Cowboys won! Don't want to ruin my mood by having the damn pc piss me off. :)  Thanks again for all the help/suggestions. Back in the morning.
October 30, 2006 12:24:53 PM

No luck with the cmos. Think I've tried just about everything possible. Still leaning towards it being the mobo now since I lose power to both cd and hdd when I plug in the ribbon cables to the mobo.

Any other explanation for this?
a b V Motherboard
October 30, 2006 12:52:29 PM

Nope.
You switched the psu out.
Processors rarely puke without:
A) massive overheating/overclocking/overvolting.
B) power supply meltdown ruining many components.

Motherboards can go south at any time.
Question is, do you want to spend $40-$50 for a socket A mobo, or $100 for a 939 cpu/mobo combo?
October 30, 2006 3:55:08 PM

Quote:
do you want to spend $40-$50 for a socket A mobo


Well there's always eBay! For fun I did a quick search for A7V8X mobos. Saw one A7V8X auction where the current bid is up to $160 + $15 shipping.

Must be a reeeeeeeeeeeeeeeal nice mother of a board! :roll:

OK, so obviously the scammers are working that auction. What's bizarre is that what appears to be a valid bid for $62.50 was posted before the scammers went wild.
That would be around $77.
For a socket A board. :!: :?

I love eBay. It always takes me back to when I was a kid, comic books were 10 cents, and Superman was making another trip to bizarro world.

-john, a dinosaur with many facets
October 30, 2006 4:33:47 PM

Probably just going to go with another socket A board. Doesn't have to be Asus or even the exact board. As I mentioned, building a whole new rig from the ground up in Feb. Not a whole lot of socket A boards out there it seems. Found a recertified PC Chips board on newegg for like $24. As long as it gets me through 3 more months, it'll be worth it.

Thanks again for all the suggestions, etc. And of course if anyone has anything to add, I'll be checking in.
October 30, 2006 10:55:46 PM

I had the same problem. Thought it was the mobo, then the HD....Nope. Just had to reinstall windows. Worked fine after that (knock on wood).
!