Review: ATI's new mainstream packs quite a punch
It's time to meet ATI's latest addition the the 4800 series, the new 4830 aimed at bargain hunters. It's hard to imagine that you'll be able to get a similar price/performance ratio with any other currently available card. We'll get back to the economics a bit later, let's focus on hardware first.
Like other 4800 series cards, the HD 4830 is based on the RV770 core, which has already brought a fair share of misery Nvidia's way. The HD 4830 uses the RV770LE core with 640 stream processors, which is a clear indication that it will end up slightly slower than 4850/4870 cards which boast 800 stream processors. The RV770 has ten SIMD clusters with 80 shader processors per cluster, so two of them were disabled on the RV770LE.
Along with fewer stream processors, the HD 4830 is also clocked slightly lower than the HD 4850. The new card is supposed to fill the gap between the HD 4850 and HD 4670 and assure AMD keeps the lead in the lucrative €100 market segment. AMD already did a marvelous job with the 4000 series and today we'll see if the new HD 4830 can live up to expectations.
The HD 4830 is positioned to take on Nvidia's 9800 GT. In case you've spent the past few months vegetating in a coma, Nvidia's 9800 GT is nothing more than a 55nm 8800GT with HybridPower support. For quite a while the 8800GT, rebranded or not, offered one of the best price/performance ratios in the market, but ATI's 4000 sries is now the new daddy. The rookie HD 4830 is available as of today, and it's already beginning to sound like a sweet deal. Well, think again. We were expecting it to retail for $130/€100, but the cheapest ones we found listed ended up costing €125, while the cheapest HD 4850 sells for €122. Hopefully, prices will drop soon, as at the moment they don't make much sense. Once it hits the €100 mark, it will be a bargain, so don't rush.
Design-wise, the HD 4830 is identical to the HD 4850. Both cards feature a fairly quiet single slot cooler and an identical PCB. Pictured below are Sapphire's HD 4870 and Diamond's HD 4850, which, like the HD 4830, has two DVI outs, a TV out and a six-pin PCI Express power connector.
The RV770LE reference clock is 575MHz, 50MHz lower than the HD 4850 and a whopping 175MHz lower than the HD 4870. The card was originally expected to feature a crippled 192-bit memory bus, but luckily AMD opted for the full 256-bit bus in the end.
Also, we were expecting to see 560 stream processors, but AMD made a last minute decision to enable an additional cluster. The fact that some samples sent out to reviewers had just 560 stream processors proves the decision was made just prior to launch. Fudo informed us about the change of plans a few days ago, and Wizzard also confirmed our report on techPowerUp. He got one of the crippled cards and had some fun with it, but don't worry, the cards with 560 will not find their way to the channel.
The memory on the HD 4830 is clocked at 900MHz (1,800MHz effective), which is ten percent slower than the 993MHz on the HD 4850. Thanks to a 256-bit bus the HD 4830 has a decent bandwidth of 57.6GB/s, while the HD 4850 has a bandwidth of 63.6GB/s. We're not sure if it's a coincidence, but its green counterpart, the 9800 GT, also has a 57.6GB/s bandwidth.
However, the bandwidth or even the higher core clock doesn't spare the 9800 GT of an embarrassing defeat, as we'll see in the benchmarks. First, let's say a thing or two about HD 4830 specs.
As we've seen in our previous reviews of RV770 based cards, ATI has managed to improve performance with filters such as antialiasing, so we can enjoy softer edges and some eye candy without significantly compromising performance. Of course, this is a DirectX 10.1 card, and finally we'll have a chance to put this API to good use, primarily thanks to Far Cry 2 DX10.1 support.
We already saw that the card relies on a 6-pin PCI Express connector for external power. ATI recommends a 450W PSU for rigs using a single HD 4830 or a 550W unit if you're looking for some Crossfire action.
PowerPlay is ATI's way of helping us reduce power consumption and save a few critters in the Amazon. It lowers clocks in 2D mode, which in turn reduces power consumption. Based on our tests we can conclude that the testbed consumes up to 230W under load, while the consumption drops to around 120W when the system is idling. For comparison, an HD4850 system consumes 250W under load and 150 in idle mode. Nvidia's 9800 GT sucks up 225W under load and 140W idling. We can see that the HD4830 is a bit better in the power consumption department, but if you've got an Nvidia chipset with HybridPower support, the 9800 GT will power down and the IGP will take over.
The next picture shows us a quite unusual situation after we ran GPU-Z. The tool shows that the GPU can run at 125% capacity, not bad.
The HD 4000 series brings us a new UVD 2.0 engine which enables dual-stream decoding along with 7.1 lossless audio over HDMI. You'll need an HDMI dongle on reference cards, but some partners such as PowerColor have already shown off HD 4830 cards with onboard HDMI.