Overclocking tests
OverclockingTwo of the three comparison cards are already overclocked when compared to the reference design, both in terms of core and RAM frequency, so the question is, just how far will each sample go?
Overclocking tests were conducted by raising core and memory frequencies of each retail card in 5MHz core and 10MHz memory steps at one time. Splinter Cell: Chaos Theory was run at 1600x1200 4x AA 8x AF, and a successful overclock was one where the cards' output was identical to a stock-clocked version, i.e. no flashing, tearing, artifacts, etc. The results were rather surprising.
| Card | BFG 7800 GTX OC | Leadtek 7800 GTX | XFX GeForce X.E. 7800 GTX | Core speed (default) | 460MHz | 430MHz | 490MHz | Core speed (overclocked) | 495MHz | 500MHz | 505MHz | % increase above default | 7.61% | 16.28% | 3.06% | Memory speed (default) | 1300MHz | 1200MHz | 1300MHz | Memory speed (overclocked) | 1365MHz | 1360MHz | 1360MHz | % increase above default | 5% | 13.33% | 4.62% |
Fully appreciating that we only had a single sample of each card and our results may not coincide with those obtained from a much larger sample, it appears as if retail cards overclock to around the same levels, somewhere in the vicinity of 500MHz core and 1360MHz RAM. The results from the Leadtek card are most impressive when viewed in percentage terms above default speeds. Leadtek, of course, is not guaranteeing any speed above the default 430/1200 clocks, so you're trusting to some luck in buying the cheaper card. Having guaranteed speeds, through a custom BIOS, incurs a price premium of between £25-£60, depending upon just how high the guarantee is. Is it worth it. Well, we re-ran DOOM 3 and Splinter Cell with each card overclocked to its stable limit.
Note how the red line, pertaining to the overclocked Leadtek PX7800 GTX TDH MyVIVO's results, shows the best improvement from the line directly above, which shows the default benchmark.
Very little comparative improvement from the high-clocked XFX card. Excellent improvement from the Leadtek, though.
