I've tried about a dozen other higher GPU engine values higher and they all resulted in a lower hash by about 100-150Kh/s lower.
What GPU engine value do you recommend I try? I've never heard of xintensity, I will definitely look into it. As a side note. I've never noticed any difference at all in performance with the following included:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
Am I doing something wrong with the above code?
You only need to run the setx command _once_ on a windows machine, and the variable will be fixed forever. If you don't do GPU_MAX_ALLOC_PERCENT, cgminer simply won't work with higher threadconcurrencies.
GPU engine depends massively on BIOS. Some 290 (and X) BIOSes will drop in performance past 1000, others drop past 1020, and still others keep climbing all the way up to and beyond 1080. Typically 1000 seems to work on everything tho, if it doesn't, try another BIOS (e.g. a different manufacture like Sapphire).
My favorite BIOSes on the 290 at the moment are:
Powercolor AXR9 290 4GBD5-MDH/O 015.042.000.000.000000 (does 930KH/s at 1499/1040 mem/engine)
Sapphire R9 290 4096 MB 015.041.000.000.000000 (does 899KH/s at 1499/1000 mem/engine - DO NOT USE THE 015.041.000.001.003747 BIOS, you will lose 20-30KH/s at the same clocks)
and
Sapphire R9 290 4096 MB Tri-X OC 015.042.000.000.000000 (does 961KH/s at 1499/1080 and 954KH/s at 1499/1070 mem/engine)
You will have to experiment a bit to find the best BIOS for your 290X.