Single 280x Claymore Zcash Mining Hashrate tapering off

[mikeisgod83]

So I have a few systems at one location using NiceHash, and on my home gaming computer i'm mining when my PC isn't in use.  The system is Windows 10, 16GB memory, single Powercolor 280x graphics card running Claymore V 12.4 mining Zcash back to nanopool with 17.10.2 ReLive drivers.  When I start mining i sit around ~305-310 Sol/s but it seems like after a while (maybe a few hours) it drops to like 150ish..., if I reboot the computer, it will start again at 305ish.  I've tried both with a mild overclock, and with stock settings.  Temp readout is 74 degrees according to Afterburner.  Any advice?  My friend told me I may need to switch do a different driver, but honestly i haven't had much luck finding any indication as to which driver, nor have I found a good repository of old drivers for these cards to try a few.  Often times i just get a link back to AMD, which only lets me download the current options.  Thanks a lot in advance.

[NotFuzzyWarm]

It's Bitcoin giving you the evil eye for even thinking about posting in a section reserved for BTC miners.

Vastly different hardware bucko Try posting altcoin questions in the altcoin areas...