Thanks a lot ;p do you think that with more ram it is possible to get higher hashrate?
No, not necessary ... yet...
Unless somebody creates a way to run higher tc on 4GB systems without increasing lookup-gap then on a 290 more is needed
I'm running 2 4GB and 1 2GB card in one machine that only has 4 GB system RAM. It can be done!
Sure it can - albeit slowly
What cards and what KH/s? They're running on YACoin, N=14
R7 240 4GB 2.9 KH/sec
XFX 7750 2GB - 2.2 KH/sec (this one doesn't overclock well)
you can compare them here to determine if they are "slow" http://yacoinwiki.tk/index.php/Mining_Hardware_Comparison
I'm not sure why you think it can only be done slowly. 4GB is a fine amount for a machine with only a couple of miners, or a number of miners with low memory. I feel I am pushing the limit of what can be done with 4 GB though, and if I ever wanted to expand, I would choose 8 GB.
Fair enough.. However the R7 240 only has 320 stream processors, the 7750 only 512. This allows much lower TC without errors for some reason. The 290 has 2560 stream processors. With a TC of 28000, a lookup gap of 2 and intensity down at 12 it only manages 75KH/s. Any increase in intensity then causes hw errors.
Using my earlier config of TC 42000, lookup gap 3 and intensity 19, i can get nearly 150KH/s. Increasing system RAM to 8GB and lowering lookup gap back to 2 gives me around 190KH/s.. (getting a new board in the next couple of days with more RAM on it - YAY!!)