make sure you have the most updated block chain b4 you start mining.

[2011-08-20 02:21:08] Started at [2011-08-19 09:57:42]                   
[2011-08-20 02:21:08] CPU hasher algorithm used: cryptopp_asm32                   
[2011-08-20 02:21:08] Runtime: 16 hrs : 23 mins : 25 secs                   
[2011-08-20 02:21:08] Average hashrate: 22.4 Megahash/s                   
[2011-08-20 02:21:08] Queued work requests: 1979                   
[2011-08-20 02:21:08] Share submissions: 46                   
[2011-08-20 02:21:08] Accepted shares: 0                   
[2011-08-20 02:21:08] Rejected shares: 46                   
[2011-08-20 02:21:08] Reject ratio: 100.0                   
[2011-08-20 02:21:08] Hardware errors: 0                   
[2011-08-20 02:21:08] Efficiency (accepted / queued): 0%                   
[2011-08-20 02:21:08] Utility (accepted shares / min): 0.00/min
                   
[2011-08-20 02:21:08] Discarded work due to new blocks: 1986                   
[2011-08-20 02:21:08] Stale submissions discarded due to new blocks: 38                   
[2011-08-20 02:21:08] Unable to get work from server occasions: 37                   
[2011-08-20 02:21:08] Work items generated locally: 809                   
[2011-08-20 02:21:08] Submitting work remotely delay occasions: 0                   
[2011-08-20 02:21:08] New blocks detected on network: 95
                   
[2011-08-20 02:21:08] Summary of per device statistics:
                   
[2011-08-20 02:21:08]  CPU 0: [112194.7 / 5.5 Mh/s] [Q:627  A:0  R:10  HW:0  E:0%  U:0.00/m]                   
[2011-08-20 02:21:08]  CPU 1: [17716.3 / 5.3 Mh/s] [Q:378  A:0  R:21  HW:0  E:0%  U:0.00/m]                   
[2011-08-20 02:21:08]  CPU 2: [1026.7 / 5.9 Mh/s] [Q:442  A:0  R:6  HW:0  E:0%  U:0.00/m]                   
[2011-08-20 02:21:08]  CPU 3: [355936499.2 / 5.7 Mh/s] [Q:345  A:0  R:9  HW:0  E:0%  U:0.00/m]                   

make  all-recursive
Making all in lib
make  all-recursive
Making all in compat
Making all in jansson
Making all in ccan
gcc -DHAVE_CONFIG_H -I. -pthread -fno-strict-aliasing -I./compat/jansson -I./lib -I./lib   -I/usr/local/include -MT cgminer-util.o -MD -MP -MF .deps/cgminer-util.Tpo -c -o cgminer-util.o `test -f 'util.c' || echo './'`util.c
In file included from util.c:35:
miner.h:33:1: warning: "alloca" redefined
In file included from util.c:16:
/usr/include/stdlib.h:237:1: warning: this is the location of the previous definition
util.c: In function 'json_rpc_call_sockopt_cb':
util.c:268: error: 'SOL_TCP' undeclared (first use in this function)
util.c:268: error: (Each undeclared identifier is reported only once
util.c:268: error: for each function it appears in.)
util.c:268: error: 'TCP_KEEPCNT' undeclared (first use in this function)
util.c:271: error: 'TCP_KEEPIDLE' undeclared (first use in this function)
util.c:274: error: 'TCP_KEEPINTVL' undeclared (first use in this function)
*** Error code 1

Stop in /usr/home/users/xxxxxxx/xxxxxxxx/cgminer-1.5.6.
*** Error code 1

Stop in /usr/home/users/xxxxxxx/xxxxxxxx/cgminer-1.5.6.
*** Error code 1

Stop in /usr/home/users/xxxxxxx/xxxxxxxx/cgminer-1.5.6.

does your install see all the cores ? (16)?  if so, did you throw it the -t 16 for 16 threads?

i get about 25mh/s on my dual QX9775's at 3.2 (8 threads)

CPU: Intel(R) Xeon(R) CPU           E5520  @ 2.27GHz (2266.76-MHz 686-class CPU)
FreeBSD/SMP: Multiprocessor System Detected: 16 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
 cpu2 (AP): APIC ID:  2
 cpu3 (AP): APIC ID:  3
 cpu4 (AP): APIC ID:  4
 cpu5 (AP): APIC ID:  5
 cpu6 (AP): APIC ID:  6
 cpu7 (AP): APIC ID:  7
 cpu8 (AP): APIC ID: 16
 cpu9 (AP): APIC ID: 17
 cpu10 (AP): APIC ID: 18
 cpu11 (AP): APIC ID: 19
 cpu12 (AP): APIC ID: 20
 cpu13 (AP): APIC ID: 21
 cpu14 (AP): APIC ID: 22
 cpu15 (AP): APIC ID: 23

Yea, that's doesn't sound right. Are you sure that the linux server is mining from both the 2 core and 16 core. With that slow mining, it almost seems that its only mining using the 2 core only.