What the hell is it?
|Graphics cards||Sapphire Radeon HD 4730||ATI Radeon HD 4770||ATI Radeon HD 4830||ATI Radeon HD 4850||ATI Radeon HD 4870||NVIDIA GeForce GTS 250 512MB||NVIDIA GeForce 9600 GT|
|Memory clock (effective)||3,600MHz||3,200MHz||1,800MHz||1,986MHz||3,600MHz||2,200MHz||1.800MHz|
|Memory interface and size (usual)||128-bit, 512MB, GDDR5
||128-bit, 512MB, GDDR5||256-bit, 512MB, GDDR3||256-bit, 512MB, GDDR3||256-bit, 512MB, GDDR5||256-bit, 512MB, GDDR3||256-bit, 512MB, GDDR3|
|DirectX/ Shader Model||DX10.1, 4.1||DX10.1, 4.1||DX10.1, 4.1||DX10.1, 4.1||DX10.1, 4.1||DX10, 4.0||DX10.0, 4.0|
|Vertex, fragment, geometry shading (shared)||640 FP32 scalar ALUs, MADD dual-issue||640 FP32 scalar ALUs, MADD dual-issue||640 FP32 scalar ALUs, MADD dual-issue||800 FP32 scalar ALUs, MADD dual-issue||800 FP32 scalar ALUs, MADD dual-issue||128 FP32 scalar ALUs, MADD dual-issue + MUL (unified)||64 FP32 scalar ALUs, MADD dual-issue + MUL (unified)|
|Multi-GPU||CrossFire - four-board||CrossFire - four-board||CrossFire - four-board||CrossFire - four-board||CrossFire - four-board||SLI - three-board||SLI - two-board|
|Hardware-assisted video-decoding engine||AMD UVD 2 - full H.264 and VC-1 decode, plus dual-stream decode||NVIDIA's PureVideo HD - full H.264 decode and partial VC-1 decode, plus dual-stream decode|
|Current etail price||£60||£80
What is it?
Here's where it gets interesting. The Sapphire Radeon HD 4730 512MB is priced at around £20 lower than the HD 4770 512MB, and such is the nomenclature that you would expect no different. Indeed, it should be slower, as well.
But take a look at the core, shader and memory clocks and they're at least as good, and better in the case of the GDDR5 RAM, leading to greater bandwidth. So what's going on? Why is Sapphire releasing a faster card with a cheaper price and lower model number?
The devil is in the details. The Radeon HD 4730 takes bits of the now-defunct HD 4830, still-available HD 4870, and hard-to-find HD 4770. Look at the 'top half' of the card and the stats are identical to a HD 4870's - 55nm production, 750MHz core, shader, and 3,600MHz memory. The memory-interface is 128 bits, matching the HD 4770's, but the number of processing cores is 640, now matching HD 4830's.
Stay with us here, folks. The important parameter in the HD 4730 vs. HD 4770 comparison is the GT/s fillrate; it's exactly half. What that tells us is that the card only has eight ROPs, instead of 16 on every other Radeon in the line-up, and that's why it will be slower than the '4770, in most cases, as that's where AA and AF take place.
So, Radeon HD 4730 has a little higher bandwidth but significantly lower fillrate/AA/AF potential than HD 4770. What's also interesting is the power-draw of the card, which is higher than HD 4770's. You'll see why on the following page.