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Video Card

From OCAU Wiki



A Video Card is an add-on card that allows information to be displayed on a screen. Video Cards consist of a Graphics Processing Unit (GPU) and dedicated memory for the GPU. The GPU gets information from the CPU and processes it to create an image that you see on your monitor. The The GPU and Memory work in the same way that a CPU would and it mainly is used to process Video or 3D and thus taking those loads off the CPU.

Major Videocard Manufacturers

  • ABIT
  • ASUS
  • ATI
  • BFG
  • eVGA
  • Forsa
  • GeCube
  • HIS
  • Leadtek
  • MSI
  • NVidia
  • Gigabyte
  • Powercolor
  • Sapphire
  • XFX
  • Xpertvision

Choosing a videocard

There are literally hundreds of videocard brands and models on the market, but the importent things to find out are the Nvidia or ATI chip the card is based on. For example all brands of 7900gt based cards will perform around the same, assuming same clock and memory speeds / amount memory. Main importance is some of the cheaper brands can be less reliable, and can often be harder/slower to RMA in case of a faulty card. Also consider any special requirements for your system. For example if you want a quiet computer, pick a videocard that comes with either passive cooling (gigabyte specialise in this), or a known quiet fan based cooler (such as HIS Ice-Q series that have artic cooling silencers installed). Otherwise you can always replace the fan/heatsink with an aftermarket cooler (see section below for suggestions). HTPC owners will need to be careful that they get a low profile videocard if the case requires it, with desired inputs/outputs (eg ATI all-in-wonder series come with tv tuners as well). Also when buying a videocard, make sure your PSU is up to the job, especially if your going SLI or crossfire.

Having a look at some Video_Card_Reviews is also a good idea.

Video card overclocking

Theres a lot of value in overclocking videocards. In particular some videocards have ram rated for higher speeds than the default. For example most ATI X800 videocards (ones with DDR3 ram), have the ram clocked at 700mhz, yet the ram chips are rated for 1ghz (2ns). Did anyone say free performance? The core of a videocard can also be overclocked, with varying success. videocard cores also often have a fair bit of headroom, due to a number of factors (manafacturing processes aren't perfect, so theres often some variation in the actual top speed a core or ram chip can do).

How to overclock your videocard

Videocard overclocking is a lot simpler than it used to be. the first thing to do is grab ATI tray tools or NVIDIA tray tools. Once you have these programs overclocking is easy. Just click the 'find max core' button, and leave computer for 20 minutes or so. What that does is the computer gradually ramps up the core, tests for a bit, until it finds an artifact (when core makes an error). Then it falls back to the previously working setting, tests for a while, and so on until the max stable core is reached. Once its done this i'd suggested ramp it down to next 5mhz, just to be sure its super stable. Once this is done click the 'find max memory' button. In fact you can do these in either order. Now your done, videocard is overclocked to the max it can handle.

Video card unlocking

Of more recent years pipelining has become more importent with videocards (a pipeline is in short an independent pixel rendering path, so double the pipelines you double pixel performance, roughly), opportunities have arrisen to 'unlock' a videocard (enabled the extra pipelines). The other factor is that ATI and NVIDIA are now increasingly selling more models off the same basic core. So the budget model is the same core as the more expensive one, only clocked a bit lower and has some pipelines disabled. The advantage for ATI/NVIDIA is twofold, they need fewer production lines so it saves money, and they can use cores that have a couple of faulty pipelines (but the rest work perfectly) and throw them in a budget model (with the faulty pipelines disabled), so less waste in the production process. However ATI and Nvidia often sell more budget models than they have faulty cores (cores only good for the budget model pipeline count) for. Additionally, there other cases, such as the (in)famous X800 pro VIVO AGP, where the card is identical in everyway (core, memory, board design) to the more expensive model, but a different bios that disables the extra pipelines to make it the budget card. In the ATI x800 pro case, one can often flash the bios to that of the higher model, and it will then work just like the higher model (and as a result, faster, thanks to the extra pipelines, and higher clock speeds). For nvidia cards, the weapon of choice has been Rivatuner, a utility that (amongst many other useful features), allows you to enable and disable pipes on your nvidia videocard without having to flash the videocard bios. If the pipes are faulty just lock them back with no harm done.

On top of this, videocards also often have vertex shaders that can be unlocked (budget card has less vertex shaders than the higher model), though performance gains are far less pronounced. Unfortunately, ATI and Nvidia are well and truly aware of unlocking, and have introduced increasing sophisticated hardware locks to stop unlocking, so there will be less and less opportunities in the future to get free performance.

Video cards that can be potentially unlocked

  • ATI 9500/9500pro/9800SE (pipes may be faulty however)
  • ATI X800 PRO AGP VIVO (almost always unlocks perfectly to X800XT or even X800XT PE, must be VIVO)
  • ATI X800 PRO PCIE / VIVO (sapphire vivo brand sometimes unlocks to X800XT, most don't. Also lots of people are having success with new X800 pro pcie non vivo cards)
  • ATI X800GT/X800/GTO/GTO2 PCIE (most don't, a couple of brands do)
  • ATI X850 PRO PCIE (most don't, some may with bridging lasercut)
  • Nvidia 6800/6800LE AGP (pipes may be faulty however)
  • Nvidia 6200 (only older NV43 revision, new NV43A revision can't be unlocked. Again pipes may be faulty.)

How to check if an X800/X850 series card can be unlocked

While just about any x800/x850 series card can be bios flashed to a higher model, whether you get any extra pipes depends on if there are hardware locks enabled. The two hardware locks are:

  • pipe disabled on-die (means pipes are faulty and impossible to unlock) - 990 reg
  • pipes disabled on gpu packaged (can be bypassed by connecting lasercut trace on gpu package, allowing unlock assuming pipes not disabled on die) - 994 reg

Typically x800/x850 standard/GT/pro cards will have one or both (usually both) of these. To check, first download Rivatuner. Then create a shortcut to rivatuner.exe. in the properties, copy and paste the following line in the target field.

"C:\Program Files\RivaTuner v2.0 RC 15.5\RivaTuner.exe" /rr990 /rr994 /rr99c /rr402c

For the 990 line, the 5th digit must be an F (all other digits irrelevent). if it isn't, the card cannot be unlocked by any means as pipes are disabled on die. For the 994 line, if the last digit is anything but F, there is a laser cut on the gpu package. connect this lasercut and this will change to an F (note there is no point doing this if 990 does not have an F for its 5th digit, since die disable overrides the laser cut). If both of these are F, the card can be unlocked. For example heres the output of my Sapphire X800 PRO VIVO PCIE (a rare breed, most x800 pro vivo pcie can't be unlocked).
Note the highlighted figures in red, which are both F (therefore card is unlockable).

Additionally it is likely to be possible for an x800gt to be 12 pipe capable, but not 16 pipe capable. In such a case reg 990 would not be an F. A bit of binary knowledge is needed here. First we need to convert the hex number into binary:

F = 1111 = 16 pipe capable E = 1110 = 12 pipe capable D = 1101 = 12 pipe capable B = 1011 = 12 pipe capable 7 = 0111 = 12 pipe capable

For all other options, your road ends here since only 8 pipes activated. If your x800gt got any of the above letters for 5th digit reg 990, drop me an email with your results snoop(at)

How to unlock an ATI 9x00 series card

With custom drivers, theres no need to do any bios flashing. The first thing is to grab the Omega drivers and install them. At installation, you will be prompted about a radeon 9500 softmod, so check that and install it. Once the drivers are all installed restart and run a few games. If your getting artifacts (eg random polygons everywhere), then uninstall the drivers and reinstall ATI drivers of choice without the softmod. Otherwise you've got a fully working 9700pro or 9800 pro and as a result card that is perhaps 50-70% faster (from going from 4 to 8 pipelines).

How to unlock an ATI X800/X850 series card

Before you commence unlocking it is important to note this will void any warrenty's of the videocard, so if you stuff things up or a bios flash fails or any other issue its your problem and you'll have to deal with it, noone else is liable but you (however email me and i'll try my best to help in such a case).

First of all if you haven't already, do the steps above to check whether the card can be unlocked. If your card failed the 994 reg, indicating the gpu package is lasercut, we'll have to deal with that. a decent guide is at

How to unlock an Nvidia 6800 or 6200 series card

Luckily the job is a bit easier here. Firing Squad has a good guide to unlocked 6800 series cards. The same process applies for 6200 (NV43 core) cards. The nice thing is if the pipes are faulty, its quite easy to lock them back again, and since we're not bios flashing, you probably get to keep your warranty. Download the latest Rivatuner instead of 15.5.

There is also a method to unlock the 6800nu 128Mb AGP permanantly so that every format doesnt involve reinstalling Rivatuner. This can be found here Unlocking a 6800nu AGP Permenantly

Video card modifications

Additionally, to get a bit more out of your videocard, many users do various hardware modifications. The most common is replacing the heatsink / fan on the graphics card with an aftermarket design. The reason is that most graphics cards come with cheap coolers, that aren't particularly good at removing heat, so have to run fans at high RPM's to keep the card cool enough. This leads to a rather noisy computer, which bothers some. Also aftermarket coolers can often run the graphics card a lot cooler (perhaps 10-20degrees C) than the default, which can sometimes improve core overclocks somewhat. It also provides peace of mind for users who are worried (often needlessly) about there card running at say 70degrees or even 90 degrees with the deafult cooler). Additionally some users often mod cpu coolers (usually involves drilling and other handyguy skills), to cool their graphics card.

Memory ramsinks: Generally there's little to be gained here, especially on newer cards. The reason is that DDR2 and DDR3 based ram tends to run so cold (due to low voltages), that they don't get any performance benefit from ramsinks (despite obvious cooling performance increase). For cards with DDR based ram, you may get small increases in performance.

Recomended aftermarket fans for videocards

Artic cooling ATI / Nvidia Silencer series: These coolers are both a lot quieter (generally inaudible), and offer considerably better cooling performance than the most default stock coolers. Also (with a couple of exceptions in older models), they direct the heat produced by the videocard directly out of the case, so case temperatures will be a little lower. While they often rather ugly, and take at least 2 slots, sometimes 3! the price and performance is excellent. Also pick your models carefully as theres a lot of variations, all suited to a particular videocard.

Zalman VF700 series cooler: Another top graphics card cooler, that offers significently improved temperatures over most reference designs. Also this one has almost universal compatability (unlike the A-C silencer series which has a seperate model for just about every different type of graphics card). Also the open fin design means that it provides airflow over motherboard components, which can be useful if theirs a northbridge nearby (especially if its not cooled by a fan).

Thermalright V1 series: Another good aftermarket cooler. Good performance. Compatable with most current model videocards. Not the easiest to install however.

Videocard voltmods

Like cpu's, videocards can often reach higher clock speeds by increasing the voltage through them. Unlike cpu's, however, ATI and Nvidia don't usually give you the option of increasing the voltage (except the new x1800xt videocards). The solution is to do some hardware modifications (careful though, you could wreck your shiny card), to increase the voltage. Additionally Nvidia 6x00 have a small amount of control of core voltage through the bios they use. For example a 6800 bios runs the core off 1.2V, while a 6800 ultra runs off 1.5V. So flash the 6800 to a 6800 ultra bios and instant volt mod. However you'll likely want an aftermarket cooler to take care of the additional heat. For hardware volt mods, see the following guides:

ATI X800 series volt mods
ATI 9600 series volt mods
Nvidia 6600gt volt mod
Nvidia 7800gt volt mod
Nvidia 7800gtx volt mod
Nvidia 6800gs volt mod

External Links

Still Confused?

send an email to:

snoop(at) (author of the material here insofar)

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