ASUS 4890

There have been many casualties on both sides during the epic struggle for supremacy between ATI and NVIDIA, with each team sending metaphorical nukes towards the other to gain a foothold.

Performance is king, and the easiest way to do this is with a whole new core - but the 4890 isn't entirely new at all. Is it enough to make a difference, and tip the scales back in ATI's favour?

We're not strangers to these cards either - we've looked at hundreds of them - and even our fair share of 4870 cards.

This isn't about the past however, so read on to see everything new and exciting about this card, if indeed there is anything exciting about it - and make sure you check out our 4890 Disassembly Guide to see what's inside.

4890 fan in motion

When the chips are down

The previous flagship single-core card from ATI was the 4870, and that was based around the RV770. As a graphics chip it was everything we could really ask for; a small die size for affordability and lower heat, and decent overclocking potential for extra gain. It had 956 million transistors, a core clock of 750MHz, and 800 stream processors.

ATI has taken this existing design, and based its new card around it - the RV790XT. This core has the same amount of stream processors, the same 55nm manufacturing process and runs with the same 256-bit memory bus, so what is different? The answer, of course, is in the clocks.

One of the main benefits of a mature manufacturing process in silicon chips (for example the Intel Core 2 CPU line) is that you're eventually left with a very high percentage of reliable, well-performing chips. ATI's had a lot of time to perfect the process by now, and this shows in the extra 100MHz core clock, and 75MHz memory clock that ATI have added to the card.

This speed increase gives a huge bump in theoretical memory bandwidth (adding 1.6 GigaPixels per second), as well as compute performance of 1.36 Teraflops. That's 10¹² FLoating point Operations Per Second, which is incredible. How did they get this huge increase - voodoo?

RV790XT core, all naked and such.

The RV790XT Core Changes

The RV770 as it was couldn't withstand this increase in clockspeed, even if it was a damn near perfect batch of cherry-picked chips for every run (which means that costs would be through the very literal roof). Instead, the RV790XT has a secret - an extra three million transistors.

Along with an increase in total to 959 million transistors, the upgraded core also packs in some very essential features, which surround the entire core. We're being literal - the edges of the chip are where these extra transistors reside. But what do they actually do?

Called the Decap ring, these three million transistors act as miniature decoupling capacitors, also known as decaps. Their purpose is to reduce signal noise, monitor the power distribution (which manages heat output), and manage the timing of the entire chip. Through monitoring of the core timing, this means that higher clocks can be increasingly stable; not only that but they can increase them at stock too - granting the 100MHz core increase mentioned earlier.

RV790 die outline, courtesy of AMD/ATI

ASUS 4890

While knowing what's inside a card is nice, now it's time to find out what it looks like - and how it performs. We grabbed a 4890 from ASUS, and whacked it down to find out just what makes it tick.

Physically the card is similar to the 4870 design, with a large red shroud covering the cooling array underneath. There is a large squirrel-cage fan (a very powerful one amp version) at the end, bringing in cool air that is passed through the aluminium fins of the heatsink. A large copper base and three very thick heatpipes move the heat away from the core, managing to keep the card at 52 degrees idle, and only 63 load. It made 59.2dBA at idle, and a rather loud 72.5dBA under stress.

Two PCIe 6-pin power connectors feed the card (which is rated at a TDP of 190W), as well as the standard two Crossfire nipples, two DVI ports and analogue video out. The cooler runs with a 4-pin PWM cable, so is controllable via software. ASUS has its latest sticker design on here too - a horseman with lightning and fire.

It's clocked at reference speeds of 850MHz core, 975MHz memory, but even with the increased clocks we managed to push it all the way to 955MHz core and 1030MHz memory - completely stable. This is a nice 12 per cent core increase and a further 6 per cent memory increase, which is quite respectable.

Performance of the single card was solid (just keep in mind that the scores are higher thanks to our Nehalem rig) compared to the previous 4870, and this has gains across the board due to the higher clockspeed and more efficient design. Crysis was particularly impressive, hitting an average of essentially 60fps. But what if you want more?

ASUS 4890 running in our Labs

Moar Firepower!

Not content with running just one of these new cards, we pleaded with ASUS to lend us another card. Thankfully our pals there agreed, and with a flourish they handed us an identical card for that thing we love most - multiple-GPU performance testing.

Crossfire with these cards works exactly the same as any other two ATI cards - simply install them both in a Crossfire-capable mobo, throw the two Crossfire ribbon cables on (one is included with every card, so you're never left wanting), and cable them up to a suitably beefy power supply.

Using a special version of the Catalyst 9.3 suite, this detected the Crossfire as soon as we got into the desktop, activated it, and off we went. Performance increased again in Crysis and GRID, though it had some serious graphical issues with 3DMark Vantage, and was in fact slightly lower than a 4870X2 in 3DMark06.

Temps only increased slightly in Crossfire, hitting 54 idle and 70 load for the top card, while noise didn't increase by more than 0.4dBA. We even hit the same OC for the single card - while in Crossfire!

Both ASUS 4890 cards in Crossfire

Wrapping up

While we'd love (and we're sure ATI would also love) to say that this is the best performing card you can buy, we won't. It's got great performance for a single-core card, and Crossfire only increases that, but the 4870X2 is still a very tempting proposition compared to the 4890.That said, for a single card that has the grunt and overclocks well - it's just what the doctor ordered.

Check out the performance below, click the link for the GPUz validation, and make sure you head into the next few pages to see screencaps of the benchmark results.

Another shot of Crossfire

Single 4890 3DMark Vantage Result: P11309

Single 4890 Crysis Benchie

Single 4890 3DMark06 Overclock Result: 18447

Crossfire 4890 3DMark06 Result: 21264

Crossfire 4890 3DMark Vantage Result: P15065

Crossfire 4890 Crysis Benchie

Crossfire 4890 3DMark06 Overclock Result: 21666