I hope someone can help me with the following:
I assembled a machine with the following parts:

ASUS KGPE-D16 Dual socket 1944 (G34) motherboard
One 8-core opteron 6128 CPU, 2.0GHz. Running at 800MHz if not loaded because of powersaving features.
8 sticks of ddr3, 1333MHz, quad channel, non-ECC, non-registered memory. Brand is GeIL.

The problem is that the benchmarks of this machine are not very good. I think the memory performance is the problem. I think that the quad-channel memory is actually functioning as single channel only.
I calculate the theoretical speed of this memory as follows:

4 channels * 64 bits * 1333MHz = 341.248 Gbit/s = 42.656 GB/s

Is this a correct calculation?

I only get about 1/8 of that number: 5100 MB/s or so . I ran the phoronix pts/ramspeed benchmark, results follow below the line.
So what is going on here? Am I maybe seeing the speed _per core_ only, so I should actually multiply by 8?
I don't think it works that way but it would explain the factor of 8.
Or is it the BIOS just does not recognize this brand of GeIL memory as quad channel?
Then it should still give me 1/4 of 42.656GB/s = 10.664GB/s. Or would that be because the CPU's clock themselves down to 800 MHz, there by cutting memory speed in less than half as well? Again I don't know if it works that way.
Should I have bought ECC, registered memory for this server/workstation board? I wanted lots of memory and speed was critical but integrity not _that_ much to justify the significantly higher cost...

If someone can give me some guidance here please, I would be most obliged...

----------------------------------------------------------------------
RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Copy - Benchmark: Integer]
Test 1 of 10
Expected Trial Run Count: 1
Started Run 1 @ 08:46:48

Test Results:
4517.8

Average: 4517.80 MB/s


RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Copy - Benchmark: Floating Point]
Test 2 of 10
Estimated Time Remaining: 59 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 08:53:31

Test Results:
4353.48

Average: 4353.48 MB/s


RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Scale - Benchmark: Integer]
Test 3 of 10
Estimated Time Remaining: 53 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:00:13

Test Results:
5222.69

Average: 5222.69 MB/s

RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Scale - Benchmark: Floating Point]
Test 4 of 10
Estimated Time Remaining: 44 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:05:56

Test Results:
4836.58

Average: 4836.58 MB/s

RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Add - Benchmark: Integer]
Test 5 of 10
Estimated Time Remaining: 37 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:12:04

Test Results:
5337.97

Average: 5337.97 MB/s


RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Add - Benchmark: Floating Point]
Test 6 of 10
Estimated Time Remaining: 31 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:17:46

Test Results:
5595.58

Average: 5595.58 MB/s

RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Triad - Benchmark: Integer]
Test 7 of 10
Estimated Time Remaining: 24 Minutes
Estimated Test Run-Time: 6 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:23:18

Test Results:
5161.8

Average: 5161.80 MB/s


RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Triad - Benchmark: Floating Point]
Test 8 of 10
Estimated Time Remaining: 18 Minutes
Estimated Test Run-Time: 6 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:29:06

Test Results:
4475.21

RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Average - Benchmark: Integer]
Test 9 of 10
Estimated Time Remaining: 13 Minutes
Estimated Test Run-Time: 7 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:35:52

Test Results:
5235.23

Average: 5235.23 MB/s

RAMspeed SMP:
pts/ramspeed-1.4.0 [Type: Average - Benchmark: Floating Point]
Test 10 of 10
Estimated Time Remaining: 6 Minutes
Expected Trial Run Count: 1
Started Run 1 @ 09:41:40

Test Results:
4905.06

Average: 4905.06 MB/s