Only 3/8 GPU used

[ssjtoma]

Hi all,
I successfully got cudaHashcat running but it only uses 3 out of 8 nVidia GPU's in the system. I tried specifying -d 1,2,3,4,5,6,7,8 but still only 3 cards are crunching on a test MD5 hash. Is that normal for short masks (4 on the left and 4 on the right with increment)?

Also, I noticed that the speed is 100x faster with --gpu-async. The cards are brand new Tesla S2050's (not GTS 8800 or similar).

Status.......: Running
Hash.Type....: MD5
Mode.Left....: Mask '?1?1?1?1' (81450625)
Mode.Right...: Mask '?1?1?1' (857375)
Speed.GPU*...: 7800.3M/s
Recovered....: 0/1 Digests, 0/1 Salts
Progress.....: 11560905932800/69833729609375 (16.55%)
Running......: 25 mins, 43 secs
Estimated....: 2 hours, 4 mins
HW.Monitor.#1: 0% GPU, 0c Temp
HW.Monitor.#2: 0% GPU, 0c Temp
HW.Monitor.#3: 0% GPU, 0c Temp
HW.Monitor.#4: 99% GPU, 0c Temp
HW.Monitor.#5: 92% GPU, 0c Temp
HW.Monitor.#6: 99% GPU, 0c Temp
HW.Monitor.#7: 0% GPU, 0c Temp
HW.Monitor.#8: 0% GPU, 0c Temp

EDIT:
Using -n 800 and -gpu-loops=1024 I got one more card running, still not sure why the rest idle. Also, interestingly the speed is lower with the extra card crunching:
Status.......: Running
Hash.Type....: MD5
Mode.Left....: Mask '?1?1?1?1' (81450625)
Mode.Right...: Mask '?1?1?1' (857375)
Speed.GPU*...: 7259.7M/s
Recovered....: 0/1 Digests, 0/1 Salts
Progress.....: 652475136000/69833729609375 (0.93%)
Running......: 1 min, 31 secs
Estimated....: 2 hours, 38 mins
HW.Monitor.#1: 99% GPU, 0c Temp
HW.Monitor.#2: 0% GPU, 0c Temp
HW.Monitor.#3: 0% GPU, 0c Temp
HW.Monitor.#4: 99% GPU, 0c Temp
HW.Monitor.#5: 99% GPU, 0c Temp
HW.Monitor.#6: 99% GPU, 0c Temp
HW.Monitor.#7: 0% GPU, 0c Temp
HW.Monitor.#8: 0% GPU, 0c Temp