The ''speed'' (amount of ghz) of your cpu depends on both the front side bus ''fsb'' and the multiplier. so atm you have 8,5x200 wich results in the 1.7 ghz you posted. However the stock multi of this cpu is 13.5 wich would result in 13.5x200= 2700 mhz = 2.7 ghz.
In short, either the multiplier went to its lowest point because you set it that way by accident , or the motherboard does that because you fiddled with something els.
Solution rather simple, simply manual set it to 13.5, where to find this is generally under the obvious tabs like ''cpu''. Althought this differs per motherboard.