Bizarre freezing/crashing on HP Pavilion a6500f Desktop PC--anyone else seen this? [ Edited ]

[wildtech02]

Before I open this thread, allow me to tell you a little bit about myself as relates to my background.

I'm a service tech with a small nonprofit org based in Seattle, WA.  My tenure there has given me six years in-field experience with many brands and models of machines which range in age from 2-7 years and beyond, so I think I know of what I speak, should there be any doubts about my expertise.

Most of the time, we get mundane malware trouble calls from our clients, but on rare occasions, a fresh-from-the-store model comes across our proverbial desk with some out-of-this-world trouble.  What follows is one of these strange cases:

A customer walked in last week from the local community college with an out-of-warranty Pavilion a6500f desktop bought at a local Best Buy in early '09. The machine would power on and test OK, but it flatly refused to start its OS (Vista) without BSODs or just plain locking up, three months after the warranty expired. Before she brought it to us, she paid a visit to the Geek Squad.  Some tech there spent time diagnosing the problem, but couldn't get a handle on it, and so ends up throwing the baffled woman to their sales dogs, suggesting she get a new PC altogether.  My God, how awful!  (And to think I already hated Best Buy for different reasons, but that's for another time.)  I don't know exactly how she got wind of us, though it could have been through fellow college staffers.  Needless to say, we took the system in.

A couple of our volunteers examined the a6500f on Monday and confirmed her diagnosis--frozen solid!  The boys are stumped.  They tinker with it a bit, but still come up with the same freeze issues.  They are unable to get any further.

I reported in on Tuesday, having come out from an under-the-weather feeling, and I tried a few things.  Still locked up.  Ran the F9 diagnostics on the thing shortly thereafter, which then tell me there's a RAM problem.  Interesting.  I pulled one DIMM away--no change.  I switched banks--nada.  Tried the same switch tactic with the other DIMM--nyet. I ran a third-party memory test utility with both DIMMs in (total 4 GB) which subsequently  finds faults in both DIMMs.  This leads me to one conclusion: replace all RAM.  We had some DDR2 memory to spare, so I asked the manager in with what we had.  Though we couldn't find any 2 GB sticks, we had more than enough DIMMs  to make a 1 GB pair that would allow the unit to run. Never mind they were slower (533 MHz) AND of another brand.  As long as they worked...

Thus, we installed a pair and booted the a6500f with 1 GB.  Eureka!  Vista started as though unharmed, and ran for a day and a half while I updated the core system and other bits.  In this time, I call HP and report my findings while the manager goes out for fresh RAM--another 4 GB kit, to be exact, and this one's clocked at what we think is the proper 800 MHz speed (it was the same as the original RAM).  It's Kingston brand.  It'll work.  Or so we thought this morning when the manager brought it through.  After a few more patches, I install the new stuff.  Three hours later...oh crap!  Complete relapse!  We are SO screwed!

Then I get the idea that this high-speed RAM may not be a good match for the system.  To rule out that the original RAM was "bad", I had it installed in a Dell machine known to be able to recognize up to 8 GB.  I ran it through the same test as was done on the a6500f.  The entire 5 GB (4+1 pairs) passed clean on the Dell.  We then install 2 GB from the Dell (it had a total 3 GB in 2+1 pairs) into the a6500f.  This is 667 MHz RAM, which once more renders the machine stable.  I'm flabbergasted! Now what?  Is there something I missed? Do we really have bad RAM, or is there some fault on the a6500f mainboard that won't allow the 800 MHz DDR2 to work properly when lower speeds are OK?  We'll be testing a 4 GB kit soon to confirm this theory.

Any clues would help, for it is not in our nature to leave customers with less than what they came in with.

And yes, the BIOS has been updated to 5.27.

Nathan Alden

Wilderness Technology Alliance 

[wildtech02]

And just to be clear, this machine really is an a6500f.  I mistyped on those last couple paragraphs.

[Big_Dave]

If you are running Windows 7 then look over this article.

[wildtech02]

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Big_Dave wrote:

If you are running Windows 7 then look over this article.

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Nice try, boss, but NO WAY!

The customer was NOT running Windows 7, but Vista SP1 when the events first occurred. The computer was updated with SP2 during testing, but not for the sake of the test; we update systems frequently as a service to our clients.  We're a firm primarily  dealing in refurb machines for the poor.  In this case, however, the client was simply a referral from a college we deal with regularly.

We have tested a total of five (5) memory kits with this unit in a week.  Let's review the results:

Kit 1 (Original Shipping) : 4 GB (2x2) Micron PC2-6400--FAILED  System boots to blank screen, or spontaneously  reboots. Vista offers repair, but hangs there as well.  Memtest86+ reports bad values stored in RAM during test, hangs in < 5 min.

Kit 2 (From Shop Stock): 1 GB (2x512M) Nanya PC2-4200--PASSED. System up for approx 18 hours without incident prior to manual powerdown  A little slow, but stable.  Was able to apply critical software patches during this time.

Kit 3 (New Purchase): 4 GB (2x2) Kingston PC2-6400--FAILED.  System up for approx 3 hours before stalling out; must force shutdown.  Restart attempt exhibits behavior as in #1.

Kit 4: (Double Swap w/ Dell 9200): 2 GB (2x1) Micron PC2-5300--PASSED. System up for 18+ hours without incident, as in #2.  #1 kit placed in Dell 9200. Memtest86+ completes one full pass on total 5 GB in Dell, no faults found.

Kit 5 (Exchange for #3): 4 GB (2x2) Centon PC2-6400--FAILED.  See #1 result.  Kit #4 reinstalled.

This almost certainly confirms my hypothesis that the motherboard/CPU combo does not support  800 MHz memory, given the FSB of the processor (800 MHz) and convention for Intel-based boards (memory speed should be below FSB in most cases) but it doesn't explain how or why the condition developed after 20 months of age (NB: age calculated from projected warranty start).

We have the customer trying things at home with the 2 GB kit, but she'd like us to find something stable.  She will return.

If anyone else has a solid lead here, I'd appreciate the help.

Nathan Alden

Wilderness Technology Alliance

[Big_Dave]

  I read VISTA that why I said "IF".  Appears to be a bad mobo or CPU.

Why are you going thru all those memory tests just to learn the same results?

[wildtech02]

Would you spend $600 on a problem that cost only $100 to fix?  Because that's exactly what Best Buy would have her doing.

The key here is that all the RAM giving a failing result was 800 MHz DDR2.  Any slower RAM passes, meaning we were able to run the system normally and to safely power off before we made any further changes to the unit.  Because the 2 GB kit above worked for us without incident, we have left this in the unit.  If we hear of any incidents from the customer over the weekend, we'll pursue other avenues to get this unit fixed or to replace it entirely.

Why go through all this?  We're nice guys.  It's what we do.

[wildtech02 · Accepted solution]

Really quick update:  Solved the case and am now able to post full findings.

We have since replaced the temporary 2 GB kit with two Corsair 2 GB PC2-5300 DDR2 DIMMs.  The affected a6500f has been running without incident for 20+ hours, and I am in fact writing this follow-up on it.

What I believe is happening is as follows:

While still uncertain of whether this is a mainboard or CPU issue, I do know that both are in play to some degree.  Why it even developed is puzzling at best.

According to the Intel processor spec database, the Pentium Dual-Core E2220's FSB of 800 MT/s isn't supposed to run in sync with the memory bus.  As the original memory was qualified at 800 MT/s (megatransfers/second), thereby matching the FSB, it failed on the board (Napa), as did two other similar kits used in replacement of the original.  All exhibited the same issue, either immediately or within a short period from startup.  Windows Vista was non-startable and non-recoverable in these cases.  Luckily, the data on the machine was largely unaffected.  We know this because two lower-speed kits passed. allowing normal function.

The current kit totals 4 GB, so it's NOT an issue of memory sizing/addressing.

To completely rule out the board or CPU, we would need to test the Napa board with a Core 2 Duo AND 800 MT/s memory, but we have no similar systems; nor would we be willing to front additional cost for the sake of an experiment.  We were fortunate to have just enough resources on hand to get as far as we did and put an end to this case.  

Thus, I will mark this issue solved, but I will also ask that other users with the same type of issue on similar hardware refer to this thread.  

Nathan Alden

Wilderness Technology Alliance

[Kericthecoolguy]

I am having the EXACT same problem. The original 2x2gb pc2-6400 800mhz ram stopped working. They failed memtest so I thought, hey, get new ram right? so I got a set of 2x2gb pc2-6400 800mhz from Gskill. BOOM not working, wont even boot. So, I try some old sticks of 2x1gb pc2-5300 533mhz. works fine of course. So I RMA the gskill. Get my replacement parts and same problem. and the worst part is the bios being locked so I can't reduce the memory timings! Tell me if you have any clue how I can unlock the bios, or what you did in end. Thanks!

[MANJACK1]

Hello there !!! i'm also trying to deal with this pc  Pavilion a6500f and my question is this: I have exactly eighteen months with this pc the protection from HP just expired few months back and the computer went with blue screen and when i try to start it, it sounds with a loud beep with out even turning the monitor on or doesn't boot at all. I will appreciate it  if you guys can tell me if this possibly the same action that was happening when your PC stopped from working. As i said, it doesn't boot at all. If this is the same problem what do you recommend me to do?

                                                                                                            MANJACK1

[Big_Dave]

manjack1,

Read this article on HP BIOS beep codes.