Eyefinity and Me - An Idiot's Guide to AMD's Multi-Monitor Technology
Memory is going to be very important here. When utilizing three monitors with the total resolution approaching 7 megapixels, both system memory and GPU memory can act as a big bottleneck. 1GB cards are simply going to limit overall performance, especially in the very latest games which can easily consume that amount of memory. On the NVIDIA side, 1.5 GB should be the minimum when running three monitors. With AMD we have the ability to buy 2 GB cards with the latest HD 6950 and 6970 cards. Or in the case of the HD 6990, there are two GPUs with 2GB a piece.
For my computer memory I chose the very affordable, yet still fast GSkill Ripjaws DDR-3 1600 2 x 4GB kit. These are currently being offered for around $75, which is a bargain. Most quad core CPUs really only require between 8 GB/sec to 12 GB/sec of bandwidth, due to their design and reliance on large on-chip caches. So overclocking memory is of little use in most applications, unless a user is willing to do things like overclock the Northbridge/L3 portion of the AMD processors. At stock speeds, DDR-3 1333 and DDR-3 1600 speeds are more than adequate. This is not true for the latest Llano based processors from AMD though, but that is not part of the discussion today.
I'm not sure what kind of deal GSkill made with the devil, but they have some of the best performing memory around at rock bottom prices. Their RMA service is actually quite good as well. Because face it... eventually most memory goes bad.
For video cards I chose to use one of my previous review products. The MSI HD6950 Twin Frozr II OC was an award winner back in February of this year. The card was stable, kept nice and cool, and had good overclocking headroom. Because this was a non-reference design, there was not an easy way to flash the BIOS to unlock the disabled SIMD units. With some luck and a few emails, I was able to come up with a working modified BIOS for this card which would in fact unlock those extra SIMDs. I chose to keep the clockspeeds standard (in this case 810 MHz core and 1358 MHz for the GDDR-5 memory), as each board only has 2 x 6 pin PCI-E power connectors. I might have been comfortable clocking them up if there were a 6 and 8 pin connection. I also must contend with my current 750 watt power supply.
MSI was kind enough to send a second board for Crossfire scaling and Eyefinity testing this past month. Essentially two unlocked HD 6950s both with 2GB of memory should be more than powerful enough to handle the resolutions I will be throwing at them. These boards retail for around $265 after rebates. I certainly would not want to use anything less than these if Eyefinity resolutions are the goal. The 6000 series broke with previous tradition at AMD in that they offer only one dual link DVI output, while the other is single link only. We also have on these models two mini-DisplayPort connections and a mini-HDMI port.
The MSI HD 6950 Twin Frozr II OC is around 7 months old now, which is something like 11 dog years in the video card business. It is still cutting edge, considering we will not see a refresh from AMD and NVIDIA until at least December of this year.
The final requirement for my setup was to get an active mini-DisplayPort to DVI connector. When Eyefinity was first introduced, a user had to spend around $100 for an active DP to dual link DVI adapter. AMD mitigated that to a point with their “Eyefinity Edition” cards, but those cards were never big sellers and their performance often did not reflect the price premium they had. The current HD 6000 parts do have a bit of a disadvantage here, as the single dual link DVI port essentially insures that one will have to buy two of the much more expensive DP to Dual Link DVI active adapter to power three 2560x1600 displays. Users who choose to stay with 1920x1200 and below monitors will have an easier time of it. The two DVI ports can power those monitors, and a $29 active DP to single link DVI adapter can be used for the third. In this case I bought the Sapphire branded mini-DP to DVI adapter.
This really is the second major category for building an Eyefinity system, and certainly the component which will likely last longer than the rest of the machine. The good news is that a user can get three 1080P LCDs for under $150 a piece. The bad news is that color quality for those screens will likely be found wanting.
Cheap TN based widescreens are at rock bottom prices. Unlike in past years, monitors are not going to be holding a user back. Ten years ago having a second monitor was a luxury, and there were not all that many video cards that supported more than one output. Purchasing a Matrox based card was the way to go, and obtaining two 19” CRT monitors would set a user back $300 or more for each unit. Current higher end TN widescreens go between $180 and $250. Considering the prices, it makes little overall sense to get a 22” or 20” panel, as their prices are not all that far below introductory 23” and 24” models. The only other reason to go with a smaller panel is due to the budget a user can spend on video cards. If price is a great concern there, then going with lower end HD 6870s would be better while pushing the lower resolution of 5040 x 1050.
If color accuracy or viewing angles are not an issue, then choosing a fast TN widescreen for around $180 would likely be the best bet. These panels typically come in around 23” to 24”, with 25” and 27” models being priced progressively higher. LED backlights will also be more expensive, and there are pros and cons to those. The pros would be the lesser amount of heat being released as compared to cold cathode fluorescents and lower power usage. The primary cons are higher prices and reduced color gamut. So that would be two strikes against TN panels if they included LED lighting when it comes to color representation. The common perception among most users is that a TN panel will give better overall gaming performance due to the faster pixel response time. There is much debate about that, but problems such as ghosting with S-IPS and PVA based panels are no longer an issue. A larger problem would be input lag caused by slower, or lower quality, panel control circuitry. There are those that swear by TN, and then there are those like me who think that factors outside of panel type have a larger impact on playability. If the panel has a really horrific scalar built into it, then input lag will be a factor no matter what type of technology that panel uses.