The 2020, rally has also been driven by increasing expectations it will become a mainstream payment method, with PayPal opening its network to cryptocurrencies.
The US dollar index rose to 90.713 after the Fed's rate-setting committee on Wednesday said its monthly government bond purchase program will continue until the economy substantially improves.
The dollar soon gave back the increase, again hovering near a two-year low. The dollar index was last at 90.2970, down 0.20%.
California-based Coinbase said on its website at 15:41 GMT it had "implemented a fix" to address "congestion issues" on its retail platform Coinbase.com and was monitoring the situation.
Network congestion was also delaying the sending of ethereum - the second biggest cryptocurrency after bitcoin.
UK fund manager Ruffer Investment Management has shifted around $675 million of its clients’ fortunes into bitcoin, an investor memo seen by Reuters shows.