No Reboot on MacPro using a new Samsung 860 EVO SSD

From the standard hard disk I can start, restart, and shutdown with no issues.

From the new Samsung EVO 860 I can start and shutdown, but I can NOT restart. It freezes with a black screen. If I remove and replace power, it will restart. Or I have to hold the power button till it shuts. The watchdog timer does NOT force a restart (I let machine sit in that state for over an hour, nada).

This is a new, fresh install on older hardware (MacPro 1,1) which has been upgraded to 8 cores with X5355.

I've done the kext mod to enable TRIM on the Samsung EVO 860, but the problem exists with or without that mod. Otherwise a virgin install.

I have (of course) reset SMC, zapped NVRAM/PRAM, including replacing the PRAM battery, run fsck in single user mode, Forced safe mode (boot-args -x) etc etc.

There seems to be something about that SSD that prevents a hot restart. But after searching for days, I cannot find what it might be that I might be able to patch.

FWIW, I put a Samsung EVO 860 in my MacBook (MacBookPro9,2) a few months ago, and have had no problems, which is why I bought the EVO for this server.

Any thoughts???

Thank you!!

Edit/Followup: Followup: I didn't realize there was an upgrade flasher for 1,1 to 2,1 – nevertheless, it did not solve the problem.

I flashed and am now a 2,1 at firmware MP21.007F.B06

I'm thinking this is more of a compatibility issue with the SMC.
SMC Version (system): 1.7f10

ALSO: When trying to zap pram just now holding CMD OPT P R the system would not go into the second gong.

TO ME this means the issue is not a shut down issue but a WARM START issue, where something is failing after power is applied and before the EFI runs or completes.

It freezes BEFORE the empty grey screen.

System and OS info:

Model Name: Mac Pro
Model Identifier: MacPro2,1 (flashed from 1,1)
Processor Name: Quad-Core Intel Xeon (1)
Processor Speed: 2.66 GHz
Number Of Processors: 2
Total Number Of Cores: 8
L2 Cache (per processor): 8 MB
Memory: 16 GB
Bus Speed: 1.33 GHz
Boot ROM Version: MP21.007F.B06. (just now reflashed)
SMC Version (system): 1.7f10

(1)(upgraded to Intel(R) Xeon(R) CPU X5355 @ 2.66GHz )

System Version: Mac OS X Server 10.6.8 (10K549)
Server Configuration: Advanced
Kernel Version: Darwin 10.8.0
Boot Volume: ServerSSD
Boot Mode: Normal
Secure Virtual Memory: Not Enabled
64-bit Kernel and Extensions: No
Time since boot: 40 minutes

Samsung SSD 860 EVO 500GB:
Capacity: 500.11 GB (500,107,862,016 bytes)
Model: Samsung SSD 860 EVO 500GB
Revision: RVT01B6Q
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Medium Type: Solid State
TRIM Support: Yes
Bay Name: Bay 1
Partition Map Type: GPT (GUID Partition Table)
S.M.A.R.T. status: Verified

Volumes:
Capacity: 209.7 MB (209,715,200 bytes)
Writable: Yes
BSD Name: disk0s1

ServerSSD:
Capacity: 499.76 GB (499,763,888,128 bytes)
Available: 474.16 GB (474,157,363,200 bytes)
Writable: Yes
File System: Journaled HFS+
BSD Name: disk0s2
Mount Point: /

The last items in the logs:
Last few lines of Launchctl LOG looks normal:

2045937     1 com.apple.launchd                            0 com.apple.fseventsd                      Removed
2045940     1 com.apple.launchd                            1 com.apple.launchd                        System: No submanagers left.
2045942     1 com.apple.launchd                            1 com.apple.launchd                        System: Done with the HopefullyExitsLast bucket, advancing.
2045944     1 com.apple.launchd                            1 com.apple.launchd                        System: Removing.
2046653     1 com.apple.launchd                            1 com.apple.launchd                        System: Removing job manager.
2046655     1 com.apple.launchd                            1 0x100404e30.anonymous.launchd            Reaping
2046662     1 com.apple.launchd                            0 0x100404e30.anonymous.launchd            Total rusage: utime 0.000000 stime 0.000000 maxrss 0 ixrss 0 idrss 0 isrss 0 minflt 0 majflt 0 nswap 0 inblock 0 oublock 0 msgsnd 0 msgrcv 0 nsignals 0 nvcsw 0 nivcsw 0
2046666     1 com.apple.launchd                            0 0x100404e30.anonymous.launchd            Removed
2046721     1 com.apple.launchd                            1 com.apple.launchd                        VM statistics (now - orig): Free: 269210 Active: -291934 Inactive: 32018 Reactivations: 0 PageIns: 35 PageOuts: 0 Faults: 101072 COW-Faults: 39688 Purgeable: -5532 Purges: 0
2046734     1 com.apple.launchd                            1 com.apple.launchd                        System: About to call: reboot(RB_AUTOBOOT).

Kernel Log

Sep  4 03:23:43 MainServer kernel[0]: systemShutdown true
Sep  4 03:23:43 MainServer kernel[0]: systemShutdown true
Sep  4 03:23:43 MainServer kernel[0]: Kext loading now disabled.
Sep  4 03:23:43 MainServer kernel[0]: Kext unloading now disabled.
Sep  4 03:23:43 MainServer kernel[0]: Kext autounloading now disabled.
Sep  4 03:23:43 MainServer kernel[0]: Kernel requests now disabled.