CrossFire: Wikis


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ATI CrossFire (also known as CrossFireX) is a brand name for ATI Technologies' multi-GPU solution. The technology allows up to four graphics cards to be used in a single computer to improve graphics performance.

Contents

Configurations

First-generation

CrossFire was first made available to the public on September 27, 2005.[1] The system required a CrossFire-compliant motherboard with a pair of ATI Radeon PCI Express (PCIe) graphics cards. Radeon x800s, x850s, x1800s and x1900s came in a regular edition, and a 'CrossFire Edition' which has 'master' capability built into the hardware. 'Master' capability is a term used for 5 extra image compositing chips, which combine the output of both cards.[2] One had to buy a Master card, and pair it with a regular card from the same series. The Master card shipped with a proprietary DVI Y-dongle, which plugged into the primary DVI ports on both cards, and into the monitor cable. This dongle serves as the main link between both cards, sending incomplete images between them, and complete images to the monitor. Low-end Radeon x1300 and x1600 cards have no 'CrossFire Edition' but are enabled via software, with communication forwarded via the standard PCI Express slots on the motherboard. ATI currently has not created the infrastructure to allow FireGL cards to be set up in a CrossFire configuration. The 'slave' graphics card needed to be from the same family as the 'master'.

An example of a limitation in regard to a Master-card configuration would be the first-generation CrossFire implementation in the Radeon X850 XT Master Card. Because it used a compositing chip from Silicon Image (SiI 163B TMDS), the maximum resolution on an X850 CrossFire setup was limited to 1600×1200 at 60 Hz, or 1920×1440 at 52 Hz. This was considered a problem for CRT owners wishing to use CrossFire to play games at high resolutions, or owners of Widescreen LCD monitors. As many people found a 60 Hz refresh rate with a CRT to strain ones eyes, the practical resolution limit became 1280×1024, which did not push CrossFire enough to justify the cost.[3] The next generation of CrossFire, as employed by the X1800 Master cards, used two sets of compositing chips and a custom double density dual-link DVI Y-dongle to double the bandwidth between cards, raising the maximum resolution and refresh rate to far higher levels.

Second-generation (Software CrossFire)

When used with ATI's "CrossFire Xpress 3200" motherboard chipset, the 'master' card is no longer required for every "CrossFire Ready" card (with the exception of the Radeon X1900 series). With the CrossFire Xpress 3200, two normal cards can be run in a Crossfire setup, using the PCI-E bus for communications. This is similar to X1300 CrossFire, which also uses PCI Express, except that the Xpress 3200 had been built for low-latency and high-speed communication between graphics cards.[4] While performance was impacted, this move was viewed as an overall improvement in market strategy, because Crossfire Master cards were expensive, in very high demand, and largely unavailable at the retail level.

Although the CrossFire Xpress 3200 chipset is indeed capable of CrossFire through the PCI-e bus for every Radeon series below the X1900s, the driver accommodations for this CrossFire method has not yet materialized for the X1800 series. ATI has said that future revisions of the Catalyst driver suite will contain what is required for X1800 dongleless CrossFire, but has not yet mentioned a specific date.

Current generation (CrossFireX)

An example of CrossFire usage – with two Radeon HD 4850 cards (Radeon R700 GPU)

With the release of the Radeon X1950 Pro (RV570 GPU), ATI has completely revised CrossFire's connection infrastructure to further eliminate the need for past Y-dongle/Master card and slave card configurations for CrossFire to operate. ATI's CrossFire connector is now a ribbon-like connector attached to the top of each graphics adapter, similar to nVidia's SLI bridges, but different in physical and logical natures.[5] As such, Master Cards no longer exist, and are not required for maximum performance. Two dongles can be used per card; these were put to full use with the release of CrossFireX. Radeon HD 2900 and HD 3000 series cards use the same ribbon connectors, but the HD 3800 series of cards only require one ribbon connector, to facilitate CrossFireX.[6] Unlike older series of Radeon cards, different HD 3800 series cards can be combined in CrossFire, each with separate clock control.

Since the release of the codenamed Spider desktop platform from AMD on November 19, 2007, the CrossFire setup has been updated with support for a maximum of four video cards with the 790FX chipset; the CrossFire branding was then changed to "ATI CrossFireX". The setup, according to internal testing by AMD, will bring at least 3.2x performance increase in several games and applications which required massive graphics capabilities of the computer system, the setup is targeted to the enthusiast market.

A later development to the CrossFire infrastructure include a dual GPU solution with on-board PCI-E bridge that was released in early 2008, the Radeon HD 3870 X2 and later in Radeon HD 4870 X2 graphics cards, featuring only one CrossFire connector for dual card, four GPU scalability.

Comparisons to Nvidia SLI

Advantages

  • CrossFire can be implemented with varying-GPU cards of the same generation (this is in contrast to Nvidia's SLI, which generally only works if all cards have the same GPU). This allows buyers who have varying budgets over time to purchase different cards and still get the benefits of increased performance. For example an ATI 5970 will crossfire successfully with an ATI 5870 , or an ATI 5770 with an ATI 5750 and so on.
  • ATI has opened the CrossFire architecture to Intel, allowing CrossFire to be enabled on many Intel chipsets which boast two x16 PCI-E slots. SLI, however, requires a motherboard which is SLI certified, which includes all nForce chipsets (such as the nForce 590 SLI, nForce 680i SLI, and nForce 790i), and most Intel X58 and Intel P55 based motherboards.

Disadvantages

  • If an OpenGL game does not have a CrossFire profile, the Catalyst AI system will set the rendering mode to Scissor by default, with no way to change it to a more suitable or faster mode, such as AFR (More information can be found at the following link: [1]). However, SLI allows the rendering mode to be set for each application manually, even for games which do not have an existing profile. It should be noted that setting Catalyst AI to 'Advanced' allows manual mode setting for Direct 3D games, but not OpenGL games, to AFR.[citation needed]

Caveats

  • The first generation CrossFire implementations (the Radeon X800 to X1900 series) require an external y-cable/dongle to operate in CrossFire mode due to the PCI-e bus not being able to provide enough bandwidth to run CrossFire without losing a significant amount of performance.
  • In some cases CrossFire doesn't improve 3D performance – in some extreme cases, it can lower the framerate due to the particulars of an application's coding. This is also true for Nvidia's SLI, as the problem is inherent in multi-GPU systems. This is often witnessed when running an application at low resolutions.[citation needed]
  • When using CrossFire with AFR, the subjective framerate can often be lower than the framerate reported by benchmarking applications, and may even be poorer than the framerate of its single-GPU equivalent. This phenomenon is known as micro stuttering and also applies to SLI since it's inherent to multi-GPU configurations.[7]

See also

References

  1. ^ "ATI Launches Crossfire... Finally". Slashdot. 26 September 2005. http://hardware.slashdot.org/article.pl?sid=05/09/26/1310207&tid=152&tid=137. Retrieved 28 December 2009. 
  2. ^ Tech Report article on CrossFire
  3. ^ HardOCP article on CrossFire
  4. ^ Anandtech article on the Xpress 3200
  5. ^ "AnandTech". http://www.anandtech.com/video/showdoc.aspx?i=2858&p=3. 
  6. ^ bit-tech review of the HD 3870, retrieved January 25, 2008
  7. ^ Raffael Vötter (2008-02-08). "Video proof: Micro stuttering may destroy the performance gains from current multi GPU technologies". PC Games Hardware Online. http://www.pcgameshardware.com/aid,631668. Retrieved 2009-11-03. 

External links


A crossfire (also known as "interlocking fire") is a military term for the siting of weapons (often automatic weapons such as machine guns) so that their arcs of fire overlap. This tactic came to prominence in World War I

Siting weapons this way is an example of the application of the defensive principle of mutual support. The advantage of siting weapons that mutually support one another is that it is difficult for an attacker to find a covered approach to any one defensive position.

Use of armour, air support, indirect fire support, and stealth are tactics that may be used to assault a defensive position. However when combined with land-mines, snipers, barbed wire, and air cover, crossfire became a difficult tactic to counter in the early 20th century.

Trench warfare

The tactic of using overlapping arcs of fire came to prominence during World War I where it was a feature of trench warfare. Machine guns were placed in groups, called machine gun nests, and they protected the front of the trenches. Many lives were lost in futile attempts to charge across the no man's land where these crossfires were set up. Though World War II had more casualties overall, the relative number of deaths compared to the number of soldiers was more than twice as high in WWI, and the soldiers died much more quickly in the battles of World War I as they went "over the top" into the meat grinder known as no man's land.

Three things changed between WWI and WWII, rendering crossfire tactics obsolete: the advance of armored vehicles (especially tanks), the advent of aerial bombardment, and the invention of the proximity fuze.

Tanks were invented in WWI specifically because they were immune to machine gun fire, and could thus cross no man's land to destroy the machine gun nests. Their armored hulls also provided cover for the infantry to advance around the tanks. The tanks in WWI were ponderously slow and prone to stalling, however, so they tipped the balance in the favor of the British, but not decisively. In WWII, the tanks improved greatly in speed and reliability, and could reach a machine gun nest at reduced risk since it spent less time exposed.

Airplanes were present in WWI, but they were used primarily for recon and the outcome of the battle in the air didn't have a lot of effect on the ground battle. The pilots often experimented with carrying things like hand grenades to drop on the enemy, but they were largely ineffective. In WWII airplanes could bomb enemy lines, rendering any large stationary target vulnerable to destruction. Fighters also strafed enemy lines with machine gun fire.

The proximity fuze allowed bombs and munitions to detonate when an object passed within a certain range (usually about 50 feet (15 m)) rather than using an impact or timed fuze. Timed fuzes are tricky because the range has to be pre-set correctly. Impact fuzes are ineffective against flying targets because they have a very small targeting silhouette, and ineffective against ground targets because the projectile has time to embed in the ground before it explodes, deflecting the explosive power upward. Proximity fuzes were developed by the U.S. Navy during WWII, and they proved instrumental in defending the fleets from aerial attack since a gunner using bullets with proximity fuzes only had to get close to hitting the enemy to knock him from the sky. Proximity fuzes were also instrumental in the Battle of Britain. Their effectiveness against German air raids is demonstrated by the fact that, after the British flak batteries changed to proximity fuzes, not a single German bomb made it past the guns. The fuze also permitted the heavy artillery to detonate above ground, permitting the explosive power to be fully utilized against targets on the ground. The trenches of WWI, for instance, wouldn't have been effective protection against a bombardment using proximity fuzes.

Any of the above three technologies would have rendered the crossfire useless. Modern warfare has not returned to big blocks of infantry because the above inventions also kill massed infantry well; to survive heavy combat in the post-WWI environment, infantry must disperse into smaller, more independent units designed to take full advantage of cover and concealment. With the perfection of shoulder-launched rockets (such as the ubiquitous Bazooka) and precision bombing, stationary targets are too vulnerable to be as deadly as the crossfire was in WWI.

"Caught in the crossfire"

This often refers to unintended casualties (bystanders, etc) who were killed or wounded by being exposed to the gunfire of a battle or gun fight.



Strategy wiki

Up to date as of January 23, 2010

From StrategyWiki, the free strategy guide and walkthrough wiki

CrossFire
Box artwork for CrossFire.
Developer(s)
SmileGate
Publisher(s)
Neowiz
VTC Game
Tencent
G4Box/Subagames
G4Box/Subagames
G4Box/Subagames
Engine Lithtech Jupiter
Release date(s)
Genre(s) FPS
System(s) Windows
Mode(s) Multiplayer
System requirements (help)
CPU clock speed

1GHz

System RAM

256MiB

DirectX version
Version 9.0c
Website crossfire-en.com

CrossFire or Cross Fire (CF) (Simplified Chinese: 穿越火线; Korean: 크로스파이어; Japanese: クロスファイア; Vietnamese: Đột Kích) is a tactical first-person shooter online PC game developed by South Korean FPS developing groups SmileGate and Neowiz. The game was released in China by Tencent, with Tencent as the exclusive agent service company. Tencent operates the game through the Internet, with service areas covered and the networks supported by China Telecom and China Netcom. The tests for its software bugs were started publicly in April 2008. It is normally believed that players of this game will naturally associate it with Counter-Strike.

CrossFire features two International Mercenary Forces, locked together in an epic global conflict. Players assume the role of either a Black List terrorist or Global Risk mercenary, joining an online team that must work together to complete objective-based scenarios. There are six online modes: Team Death Match, Search and Destroy, Elimination Match, Ghost Mode, Free-For-All and the all-new Special Mode . Based on their performance in-game, players will receive experience points and be promoted through various Military Ranks. Players will also have the ability to customize their character's equipment and appearance through CrossFire's in-game item shop. Upon release, CrossFire will be free to download and playable online.

Story

A number of soldiers who once belonged to the world-leading Special Forces joined 'Global Risk', the international mercenary forces corporation.

The mercenaries carried out difficult missions for the organization, but they have distinctive differences from 'Black List' who commit terror only for profit. Despite an appreciable sum of money, the mercenaries have never participated in any battle without justifiable reasons and they live up to their conviction to fight against terrorists. Based on their practical battle experiences and skills, Global Risk seeks to expand its power.

Main clients of Global Risk are third world countries without their own national militaries, countries on the black list of terrorists, and the UN X-File Bureau implementing secret missions.

Black List is another mercenary corporation which sponsors terrorism.

Its founder is unknown and it is a secret terrorist organization. Hence, it is the only mercenary corporation free from legal commitment to any country. Black List is run by Hedge Fund, which controls the diamond market in England. Its main clients are mostly poor and weak countries.

Ostensibly, it seems to be a simple terrorist supplying company, but it has its own justifiable reason to advocate the interests of powerless countries.

A large percentage of Black List mercenaries are from the Middle East.

Global Risk is a huge military organization without a national identity and is composed of discharged soldiers of Special Forces.

It was initially founded by Sir Alex Roid, who was a retired SAS member in British Air Force. Then the Australian-born American businessman, Michael Norman, developed it in the form of a business corporation. On the basis of his principles, the expressions of a desire for peace and cooperation of the world, Global Risk is implementing a terror purge with secret operations to achieve lasting peace for the world.

However, some make accusations against Global Risk because Global Risk is relying too much upon powerful countries and their wealth without any justifiable reason as a business corporation. In fact, a number of competent members ran away while carrying out operations based on idealistic peace theories introduced by powerful countries like America or England.

The special force troop, GRX, has developed a partnership with UN X-File Bureau. The Allies operate missions effectively; the Bureau plots and plans, and GRX carry out the missions. However, their secret missions have never been exposed to inside or outside troops.

Table of Contents

CrossFire/Table of Contents

External links








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