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DELL Precision T7400: CPU or mainboard problem?

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June 22, 2012 5:50:33 PM

Hello guys,

since a few weeks my DELL Precision T7400 occasionally freezes (no blue screen). Restarting it immediately after a freeze doesn't work (screen doesn't go on, remains black), so I have to wait a little bit, maybe an hour (until it cools down probably). When it finally restarts, I get the beep code 1-3-2 (memory problem). My next step then is to take all RAM modules out and to try them one-by-one. When a bad module is detected, the mainboard beeps (1-3-2), when a good module is detected it starts with memory problem error message. I then replace the bad module and it works... until the next freeze occurs.

Since last friday I have a (new?) problem: I can't start Windows anymore. When the Windows splash screen shows up, the workstation restarts. Tried to start Windows in safe mode, but every time the classpnp.sys is loaded, the system restarts... and this again and again. My first thought was: Maybe a windows problem. Tried to start Windows from the installation DVD, but this resulted in the same problem. Then it must be hardware. RAM? I tested RAM with Mem86+ (tested only one pass), no errors at all, memory seems just fine. Must be another problem.

Then I downloaded Dell Diagnostics 32 Bit, created a bootable USB stick and started diagnostics. The result: All tests green except "L2 Cache (Multiprocessor)" !!! Running one of these tests (Dirty Cache Reads Test, Alternating CPU Writes Test, Random Access Thrash Test) results in an immediate system restart (test starts, screen goes black, reboot). In "L1 Cache (Multiprocessor)" both "Dirty Cache Reads Test" and "Alternating CPU Writes Test" succeed, but the "Random Access Thrash Test" fails (restart).

The "L1 Cache" and "L2 Cache" test (Pattern, Walking Bit, MATS) always succeed, only "L1 Cache (Multiprocessor) / Random Access Thrash Test" and "L2 Cache (Multiprocessor) / All Tests" fail. Since the workstation immediately restarts, I can't tell which error exactly occurs. Dell Diagnostics doesn't write any logs back to USB stick.

What do you think? Is it really a damaged CPU? Or could it be a mainboard problem? Same or comparable problem anyone?

Any help is very much appreciated!

Config:
- DUAL INTEL XEON X5482 3,2GHz
- 16GB DDR2 800 QUAD CHANNEL FBD MEMORY
- 4 x SAS (1 x 146GB, 3 x 300GB)
- C17 SAS NO RAID FOR 4 HARD DRIVE
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June 23, 2012 6:38:34 AM

Although bad CPU's are very rare...u cud be one of those very unfortunate persons:) 

However, i'd really like to check ur RAM sticks again properly.....

I had a friend whose comp used to get stuck just like urs, ran mem test for an hour, and it passed with flying colors....so the problem went on for months without any cure.....Then one fine day he pulled out the sticks, cleaned them and put them back.....and.....ta da!!! no more problems!!! apparently there are some RAM issues which even memtest can't detect!!
June 25, 2012 5:40:35 PM

Shawn, thx for your input. It seems to be the CPU! I took one of the two CPUs out and with one CPU it works like a charm. In a few days I will try to clean and reseat the other CPU (waiting for Arctic Silver thermal compund & ArctiClean to be delivered). Maybe this will solve the problem. If not, then I will have to get a new CPU.
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June 26, 2012 2:11:32 AM

All d best :) 
December 7, 2012 1:00:29 PM

PrecisionGuy said:
Shawn, thx for your input. It seems to be the CPU! I took one of the two CPUs out and with one CPU it works like a charm. In a few days I will try to clean and reseat the other CPU (waiting for Arctic Silver thermal compund & ArctiClean to be delivered). Maybe this will solve the problem. If not, then I will have to get a new CPU.


I have a T7400, and the memory slots began going bad.
I had a Dimension 9400, and the memory slots went bad on that one too. After 2 motherboard replacements on the Dimension, I threw it in the trash. Dell offers only used motherboard replacements under warranty. They also "cheated" on their electronic parts, and had a lawsuit by a large corporation. "Foul play" was discovered by the upper level bureaucrats, and they were heavily fined.

My "guess" is that your m.b. is going bad, just like mine have.

Have you found a source of new T7400 m.b.'s you can refer me to?

... Chris
!