Sapphire HD5770 Crossfire Review
When testing a GPU it's always important to make sure that you have a setup capable of delivering all the data the cards can cope with. CPU limitation is difficult to overcome as you start having plentiful cards, but we're confident our i7 920 overclocked should be able to handle the pressure.
Motherboard : ASUS Rampage II Extreme
CPU : Intel i7 920 @ 3.6GHz
RAM : 6GB Corsair Platinum @1333mhz
PSU : OCZ 1000w Gold PSU
HDD : 1TB Samsung Spinpoint F1
Monitor : Samsung 2433 24" @ 1920x1200
OS : Windows 7 Ultimate 64
GPU : Sapphire HD5770 x2, ATI HD5850, ATI HD5870
We're putting the HD5770 Crossfire setup against its two main rivals. On cost terms it is the HD5850, and from our experience with the HD4870 we're including a HD5870 for performance testing. That's a steep challenge indeed as the HD5870 is an exceptional card.
The standard Sapphire HD5770 comes with a core speed of 850MHz and a GDDR5 speed of 1200MHz (4800MHz effective). Of course we always enjoy testing the product you can purchase and play without mucking about, but we're hardware nuts first and foremost so we're also going to see if the HD5770 can overclock as well as the HD5850 does.
The most important thing to remember about overclocking is that pure numbers are meaningless if the heat generated is too much, or if we run into stability issues. Because the Sapphire HD5770 already nearly maxes the overclocking sliders on the Catalyst Control Center, we turned to MSI Kombuster for our overclocking and stability testing. This is a neat combination of RivaTuner and Furmark, in that we can increase speeds, check temperatures and stability, obtain a benchmark and go again, all within a single program.
Firstly we wanted to see what temperatures we had at stock and therefore how much headroom the cooler allowed us in our quest for absolute performance. Running the test at 1900x1200 with no anti-aliasing gave us 71°C maximum, which should give us quite a bit of room to play with. Upping the anti-aliasing to 8xMSAA and we still obtained 71°C. Nice.
By using the tried and tested method of upping the core speed a little at a time and endlessly testing until we reached breaking point, we got to 960MHz core clock and the GPU was still only producing 75°C in the very demanding benchmark regardless of if we had no AA or 8xMSAA.
We'd love to have gone on further but sadly that's as far as our slider goes. Nonetheless 110MHz should see a nice little performance boost. We then turned our attention to the GDDR5 and managed an increase from 1200MHz to 1400MHz before we started to get artifacting. Normally manufacturers run the RAM as hard as they can get away with, so it was great to see Sapphire giving us so much headroom.
Does all this power equate to good value?