CPU-mobo doesn't boot up

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I just bought a used CPU-motherboard combo that doesn't work. The
forum member I bought it from has agreed to refund my money after
I return the items, but I want to make sure they really are
defective before I send them back.

The CPU is a Phenom II x4 955 BE and the mobo is an Asus M5A88-M.
I already had the RAMs which are 4x2GB Corsair XMS3 1600 MHz, all
tested OK. The CPU fan spins when I turn it on but no display and
no BIOS beep. The on-board memory indicator LED, which the manual
says should light up with incompatible memory, remains dark.
Here's what I've done so far:

1. Tried with 1 and 2 RAM sticks at a time and changed slots.
2. Tried with both IGP and discrete graphics card.
3. Tried with 3 different good quality PSUs working in other
4. RAMs are tested and working in another computer.
5. Also tested with RAM from another working computer.
6. Tried onboard memory tuning.
7. BIOS cleared (CMOS battery is currently 3.03V)

All of the above tried with all other devices disconnected (HDD,
optical drive, printer, etc.). I placed the motherboard on a
paper magazine, which is my usual method when testing a new rig,
so there's no possibility of something being shorted by the
mounting. For the power switch, I use a non-latching switch with
a 0.1" rellimate connector that plugs onto the mobo header.

Is there anything else I could try? Does anyone know of any quirk
of this mobo model? Thanks in advance for any helpful input.

Re: CPU-mobo doesn't boot up

Hobbyist wrote:
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Place on paper magazine.

Install CPU, heatsink, connect heatsink fan to fan header.

Do not install RAM.
Do not install video card.
Do not connect disks.

Connect ATX power supply 24 pin main lead, as well as
the ATX12V 2x2 CPU power cable. The 2x2 has two yellow wires
and two black wires. The CPU VCore runs from +12V, and
the yellow wires are the +12V.

Connect front panel POWER switch to power terminals on PANEL header.

Connect computer case speaker, the one with the cable labeled
"SPKR" on the end, to the speaker pins on the PANEL header.

Turn on the PSU.

Press the power button.

Expected result:

Computer case speaker should "beep" the missing RAM error code.
The CPU is needed to make the beeping sound. If it passes this
test, and you get a two or three beep error pattern, you know
the CPU works a little bit, power supply works, chipset is OK.

That doesn't test storage ports, RAM socket, video card PCI
Express slot or anything. But it's a good first test to try.

If the test fails, and the speaker remains silent, it could be
a bad CPU or bad motherboard. Since the fans spin, the power
supply delivered +5VSB, the PS_ON# signal from motherboard
to power supply works, and the power supply sent back the 12V
to run the fan. So that much appears to be working. Doing
the beep test, might tell you a little bit more.


Re: CPU-mobo doesn't boot up

Paul wrote:
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Thansk for your interest. I tried out your suggestion to power up
without installing any RAM stick. No beep at all. So it looks
like either the mobo or the CPU is dead. Agree?

The seller insists that he was using the pair shortly before
shipping them and they were working perfectly. Reading between
the lines of his messages, I'm inclined to believe him. I suspect
that he unknowingly damaged either item when he disassembled his
rig. He posted a photo of his machine with an after-market cooler
but sent the stock cooler (we agreed on that beforehand). He sent
the motherboard and the CPU+stock cooler in their original
separate boxes.

Re: CPU-mobo doesn't boot up

Hobbyist wrote:

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Regardless if you get it to work send it back it's most proberly been gamed.
I had a phenom ll x6 1075t when they go they go. it worked fine when doing
normal use but when playing games ouch!!!!. If you play a game like battle
field 3 and see a player trying running but going no where their rig has had
it. that was me. i did not get it until i saw some else.

Re: CPU-mobo doesn't boot up

On 12/22/2012 11:36 AM, Hobbyist wrote:
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In addition to the 24pin power supply connector, you didn't forget the
four pin connector did you???


Re: CPU-mobo doesn't boot up

philo  wrote:
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No. I _have_ occasionally made that blunder in the past and will
probably do so again in the future, but not this time (I've
assembled perhaps a couple of hundred PCs and worked on many
more). I was wondering if a mental block could have caused me to
miss some logical step in the diagnostic process.

Re: CPU-mobo doesn't boot up

On 12/23/2012 07:23 AM, Hobbyist wrote:

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I too build hundreds of machines and don't think you missed anything...
however there is one thing I've done a couple of times that worked:

Remove the CPU then put it back in.

In two instances that did the trick.
It's a very slim chance but worth trying if you've done all else.


Re: CPU-mobo doesn't boot up

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I agree with Philo.
While the CPU is out, carefully inspect the pins/pads.
Jostling in shipping could cause some shifting and misalignment.


Re: CPU-mobo doesn't boot up

Chris S. wrote:
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If the processor is a PGA (like an S478), check for broken pins.
Occasionally a user misses the fact that one snapped off. (There
used to be a guy who would solder them back on for a price, but
he's quit the business.)

2/3rds of all electrical signals, are power and ground. And a lot
of those can be snapped off, without causing a failure. But
things like data bus signals, snapping those off will prevent
booting. If a power touches a ground, well, that's not going to
have a good result.

If the processor is a land grid array (flat gold contacts on the CPU),
then your focus shifts to the LGA socket on the motherboard. It's
easy for the brittle springs to get busted off. Sometimes, a motherboard
box gets crushed in shipping, and the PNP cap can't protect the springs
from the forces involved. I don't really think it's possible to
do much with those springs, as they don't have enough flex left in
them to be corrected with a pair of pliers. At least with PGA
processors, you could take a ball point pen refill, slide it over
a slightly bent pin, and straighten it up. LGA springs, don't
really look that repairable. A PGA pin bent 90 degrees, will
snap off when you straighten it.

Even brand new motherboards, with not a mark on the motherboard box,
have been known to have a massive number of springs bent or crushed.
So these things happen.

For a couple of the motherboard companies, there are videos
available showing the two minute functional test the motherboard
gets at the factory. So every motherboard in that case, has had
at least one CPU inserted into the socket. Which makes it so hard
to understand how the springs get bent. They couldn't very well
bend them before the two minute functional test, without
the board ending up in the repair pile.


Re: CPU-mobo doesn't boot up

On Saturday, December 22, 2012 10:36:17 AM UTC-7, Hobbyist wrote:
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 light up with incompatible

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Yikes.  Magazine paper is shiney and great for building up static
charge.  Plain newspaper is a lot safer, but I'd still rather use
anti-static sheet, such as the thin foam pad included with every
new motherboard or some pink anti-static bubble wrap.  Even a
metalized anti-static plastic bag turned inside-out is safe,
provided it doesn't touch the motherboard.  Black anti-static
plastic bags are safe on both sides but probably shouldn't touch
the motherboard because they conduct slightly and will measure
about 10 megaohms over a span of an inch.

How careful was the seller in avoiding static damage?  I've seen
many Ebay items photographed directly on top of tables or carpets
with no static protection, and some shippers use regular foam
packing peanuts, even when the product isn't enclosed in a
metalized anti-static bag.

Is there any way you can test the CPU in a known good motherboard?

And despite the fact you've tried the Corsair memory every which way,
can you test with some 100% trustworthy memory, something with
name brand chips that definitely aren't overclocked, as they are with
those Corsairs?

Can you attempt a boot block BIOS update?  I don't know how to initiate
that with an Asus, but some motherboards will try if you hold down
certain keys while turning on the power or if a BIOS file is on a USB
flash drive plugged into the motherboard.  You may have to use a
separate video card to see any activity during this.

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