k2kev When capturing, it captures at 128fps for a while and then drops to sub 1fps for a while.
That sounds almost like some fast FIFO is filled, and the secondary memory (hard drive?) is causing the slow frame rate. This does not sound like a ZWO problem, but a local problem.
Try using an SSD. At the prices today, there is no reason not to use an SSD.
If you are not using an SSD, and your computer has the good gen2 (x2) USB 3 ports, you might want to try the Samsung T9 as a cheap test (they are faster than T7, which in turn are faster than T5). Make sure the SSD has the capcity to hold your entire session, or you would be back to square one at some time.
I assume that yopu have probably already done this exercise, but I will repeat it... using 16 bit transfers, the ASI174 needs about 5 MBytes/frame. At 160 FPS, it takes about 0.8 GBytes/sec SSD writes to keep up once the FIFO is filled.
The T9 is good up to (depending on your computer's I/O) 2 GBytes/sec. The T7 is good to 1 GBytes/sec, and the T5 is about 0.55 GBytes/sec. The T5s are so obsolete that they are probably more expensive than the T9. Make sure you don't make the mistake. :-)
Make sure the program is using the SSD as its backing store.
Chen
