Not so sure the speed of the cpu is so vital after reading
this review, as long as its a decent cpu and not too old. This also shows how capable the 5770 is even at 1920 X 1080. And the price difference between 5770>5850 is more like £100.
Oh and 5850\5870 if money dont matter.
5770 is definitely a great performer for its price, however CPU speed DOES matter (well, not so much for 5770). The reason that the result in that review Core i5 750 2.66GHz (stock speed) vs 3.8GHz with a 5770 is almost identical is because the Core i5 750 at stock speed (2.66GHz) is already fast enough to use 5770 to it max capability, therefore overclocking the CPU further would not increase the frame rate any further.
However if you look at the following:
Test kits: HD5870, 4GB Corsair 800Mhz DDR2, 4GB Corsair 1,600Mhz DDR3
Crysis (DirectX 10, 64-Bit, High) at 1,680x1,050
[email protected] (stock speed)=12-35fps
Q6600
[email protected]=24-45fps
[email protected] (stock speed)=19-36fps
E8400
[email protected]=27-48fps
Phenom II X4 965 BE (C3 stepping) @3.4Ghz (stock speed)=23-46fps
Phenom II X4 965 BE (C3 stepping)
[email protected] =29-52fps
Core i5
[email protected] (stock speed)=20-50fps
Core i5 750
[email protected] (stock speed)=33-57fps
(source: Custom PC Issue 078 March 2010, p41)
This clearly shows the CPUs are in fact not keeping up with 5870, otherwise the frame rate would remain the same even with faster CPU speed, just like in that review where the frame rates of Core i5 750 2.66GHz vs 3.8GHz on the 5770 remaining identical.
I'm not saying it is completely pointless to get an 5870 or 5850 to pair up with an average CPU, but if comparing a person that uses a Dual-core at 3.8 GHz to a person Quad-core at 3.8GHz, the person using the Dual-core CPU would effectively only be using only half the capability of the 5850/5870 comparing to the person using Quad-core of the same speed in games such as Battlefield Bad Company 2. Just have a look at the following test result, and look at the result for Battlefield Bad Company 2:
http://www.overclock.net/pc-games/659536-contagion-review-dual-core-vs-quad.html
(Just a reminder a 4870x2 is roughly around the same speed as 5850/5870).
So let's say we compare E6600 to Q6600, both at 3.6GHz...with a 4870x2/5850/5870 in Battlefield Bad Company 2...if E6600 get 35fps, then Q6600 would be getting like 70fps- because of the extra 2 cores.
Which bring me to the point that...you are paying full amount for 5850/5870 as everyone else, but comparing to people that got Quad-cores, you'd only be getting half the performance in return in the current and future games that are designed with support for Quad.