Ask Dan: Video cards of all shapes and sizes

Date: 6 February 2008
Last modified 03-Dec-2011.


More very simple choices

Will the Gigabyte GA-P35-DS3P motherboard run two video cards in SLI?


That board's got an Intel chipset, so no. You need an "SLI Certified" board to use SLI, and that means almost nothing but Nvidia chipsets.

These days, if you wanted to run a top-spec CPU and/or overclock, you'd probably be wanting an nForce 780i board of some sort, like an Asus P5N-T Deluxe, yours for $AU451 delivered from Aus PC Market here in Australia (Australian shoppers who'd like to order one can click here to do so).

Real show-offs might prefer the $AU484-delivered Asus Striker II Formula, which adds on-board power and reset switches (which beats bridging the pins with your car key when you're fooling with the mobo with no case switches plugged in) and its own little LCD and LED indicators for boot errors and component voltages. Australian shoppers who simply have to have these extra features, or are merely willing to pay the extra $33 they cost, can click here to order a Striker II.

Intel's new top-end Socket 771 "SkullTrail" platform is the only non-Nvidia chipset that's SLI Certified, but it's not worth buying if you don't intend to make an some eight-core super-behemoth, or a specialised game development box, or something. SkullTrail is really a server board with a gaggle of video card slots, not a solution for "enthusiasts" who're on any sort of sane budget.

You can, however, use two ATI graphics cards in "CrossFire" configuration on a twin-graphics-slot Intel-chipset board like this one (or on the a SkullTrail board, for that matter). CrossFire is ATI's equivalent of Nvidia's SLI.

There have also been a series of oddball two-chip-on-one-card graphics cards that give you SLI or CrossFire in one physical card. Most of them have been pretty forgettable products, but the newest one is the ATI Radeon HD 3870X2 - two Radeon HD 3870s on one card - which is a real contender in the very high end gaming market. Performance varies depending on the games you're running, but a 3870X2 costs less than a pair of GeForce 8800 GTs, is generally noticeably faster than them, and only needs one motherboard slot.

(Real lunatics can, in theory at least, run a pair of 3870X2s on a twin-slot motherboard, for a total of four Crossfire-d graphics adapters. If you're not building a demo system for a computer show, I have no idea why you would want to do this.)

Here in Australia, Aus PC Market will be pleased to sell you a Sapphire-branded HD 3870X2 for a mere $AU599.50 including delivery; Australian shoppers can click here to order one.

Note that all multi-card or multi-GPU-on-one-card solutions have the same problem: Each adapter has its own memory, which basically duplicates what's stored in the other adapter's memory. So two 256Mb cards cannot hold any more data (textures, geometry data, screen buffers, et cetera) before running out of memory than one 256Mb card could.

But the doubled memory (a total of 1024Mb, in the case of most dual-card solutions today, and the 3870X2), creates that large a memory "hole", which I talk about in more detail in this Ask Dan.

So if you install a pair of 512Mb cards or a single 1024Mb one, you probably won't be able to prevent your graphics adapters from "covering" the whole fourth gigabyte of your system memory. If you're running a 32-bit operating system, this means you will definitely not be able to see more than 3Gb of system RAM under any circumstances (actually a bit less, as I explain in that same piece).

If you're running a 64-bit operating system and install more than 4Gb of RAM, it's theoretically possible that you'll be able to move the memory holes out from over the memory, or the memory out from under the holes, but in practice you'll probably still "miss out" on a bit more than a gigabyte of your installed RAM. So if you install 8Gb, you should only expect to be able to see something like 6.9Gb.

DDR2 RAM is so cheap these days that, as long as that's the kind of memory your computer uses, this problem is no longer important if all you're worried about is value for money. Two 2Gb memory modules can actually cost you less these days than two 1Gb modules and two 512Mb ones, so you might as well buy the 2Gb modules even if you know you won't be able to see the fourth gigabyte.

And 2.9-odd gigabytes of memory is still enough for a very nice 32-bit gaming and productivity box.

But it still pays to know about this, so that you don't tear your hair out thinking that there's something wrong with your PC's RAM.

(Also note that the 32-bit version of Windows Vista only ever lets you have a maximum of 3,120Mb of RAM anyway.)


Meanwhile, in the cheap seats...

I currently have an AGP GeForce FX 5100 with 64mb of DDR RAM and I need to upgrade it to a better card with at least 256Mb. I'm trying to run a flight simulator - would this Galaxy GeForce FX 5500 be good enough?


Depends on the flight simulator.

If all you need - all you need - is more memory for textures and/or screen resolution, then sure, a cheap (under $AU70 delivered, as I write this) 256Mb card like that will probably do you just fine. Many flight sims load the graphics hardware pretty lightly; you don't need a whole lot of polygons per second if other planes are usually dots in the distance. And unless you're playing a twitch-game combat flight simulator, you probably don't need sixty frames per second, either (though it'd still be nice to have).

The 5500 probably won't be noticeably faster than your current card whenever RAM is not the limiting factor, though. The 5100 is such a cut-down card that it's not often even included in lists of GeForce FX cards, but I think it's just a lower-clocked FX 5200. Or perhaps 5100 is another name for the version of the 5200 with a 64- rather than a 128-bit memory bus.

Either way, there's not much variation in the FX 5x00s until you get to the 5600 and above, where the clock speeds start climbing faster.

Note that all of these cards are 2002 technology, which is pretty freakin' ancient by video card standards. You can't put any truly current card on an AGP motherboard, but you can get a way faster card than a 5500 for not a lot more money.

Aus PC Market, for instance, still have an AGP 256Mb Radeon 9600 Pro (which is 2003 technology!) on offer, for only $AU89.65 delivered as I write this (Australian shoppers can click here to order one).

That Radeon will be comfortably 50% faster than the FX 5500 for just about anything, and it's based on ATI's R300 core supports the full suite of DirectX 9.0 features. The FX cards go on to support DX9.0b as well, but so slowly that it dosn't really matter; neither card supports 9.0c or later. You really want a 9.0c-capable card for general purpose 3D gaming these days.

(In case you care, a full DX9.0c video card is also one of the requirements for the 3D "Aero" interface for Windows Vista. Microsoft Flight Simulator X also requires a 9.0c card. The GeForce 6 series was the first Nvidia hardware to support 9.0c; the R520-core Radeons are the matching ATI parts.)

You'd get a noticeable extra performance boost if you stepped up to a $AU132-delivered GeForce 7600 (2005 technology!), which Aussie shoppers can click here to order. But, as I said, it depends on what you actually need from a video card. The 7600 is a full DirectX 9.0c card, and would run games like Doom 3 and Half-Life 2 quite nicely, and also let you wind up the pretty-settings a bit in Flight Simulator X.

I wouldn't buy a faster AGP 3D card than a 7600, unless I got it cheap on eBay or something. Anything more than $AU150 is definitely better put towards your Whole New Computer fund.

After I sent the above to Leon, he got back to me as follows:

The flight sim I'm running is the Phoenix R/C aircraft simulator, and it was running OK. After I downloaded the 1.05c update some of the screens won't run properly (they stop and start). The box says it needs a minimum of a 128Mb graphics card to run properly.

I'm getting between 30 and 40fps in some sceneries and only 5fps in others. At 30fps it runs ok but still has some slight hiccups.

My system consists of Sempron 2800+ 2.0ghz, 2gb DDR and a 250W power supply. I wasn't sure if the two cards you stated would run OK off the 250W supply.

The specs page for Phoenix does indeed make it look pretty lightweight, by current 3D game standards - but I think the Radeon 9600 is still very justifiable.

Your very variable frame rate is a classic symptom of running out of graphics card memory. When the computer suddenly has to start pumping stuff like texture data from main memory rather than caching it all on the card's own RAM, it's normal for framerate to dive massively.

If you've got a real 250 watt power supply then you may be OK; I don't think the GeForce FX 5500 or Radeon draws a lot more power than your current card. But most PSUs can't actually deliver anything very close to their rated power, so yeah, I'd budget for a PSU upgrade as well.

This doesn't need to be a big purchase either, though.

$AU71.50 delivered gets you a "430W" Thermaltake (Aussies can click here to order!), which is probably good for a genuine three hundred and something watts for years on end. That'd probably be more than enough for you. And less than ninety bucks gets you a "500W" GTR-branded PSU (click here to order that one). It's probably a genuine 400W unit, which'd give you plenty of room for expansion.

Australian shoppers can buy all sorts of video cards from Aus PC Market.
Click here to order!