Radeon 4670's memory controller pays dividends

EARLIER TODAY, WE told you about ATI's new mid-range cards, the 46xx series. The specs seem pretty solid, but there are a few interesting bits on top of that.

The card will not set the world on fire, but it is a much better step up than usual, with almost three times the shader count of the last generation 3650 card.

Other things go up by lesser amounts, so don't expect performance to go up by that much. Memory bandwidth is up by about 25 per cent, and this is likely a gating factor in performance.

Sapphire HD4670 with 43 per cent more sword-bearing chick

What can you do? Add more pins, add more board layers, more memory width, pile on more expensive memory. That can work. See the 4870's crushing performance for what you can do with narrow and fast GDDR5, but that is really tough to do on an $80 card. This segment is all about price, so you do what you can and balance things out where you are able.

This market segment is delineated in about $20 chunks, an $80 card is a different category from a $60 and $100 card. Some people even differentiate on $10 or less while OEMs are more granular than that.

It is all about the Benjamins, but usually doesn't even hit one of those. Price matters a lot, and if a card maker can save $2.50 in parts, that usually translates into a $5 drop in end-user pricing. Do that twice and you end up with a card that is one category up on the others it is competing against. This is a significant advantage.

That is where the 36xx line's secret weapon comes into play. The memory controller on the GPU supports not only the dirt-standard DDR2 and de rigeur GDDR3, but it also now will take vanilla DDR3. The point here is that GDDRx is a graphics memory that has limited and specialized uses, and the volume, while high compared to some things, is minuscule compared to desktop RAM.

GDDR3 and DDR3 are more or less the same in terms of functionality, it is just that DDR3 is half a decade newer than the G prefixed part. What does that mean? You can swap them out on a technical level with gains or losses in bandwidth measured in rounding error terms. If your controller supports it, pick your poison.

If you choose GDDR3, you are on the GPU memory pricing curve. If you pick DDR3, you are on the mainstream RAM pricing curve. Guess which one is has more competition? A quick check of pricing shows that a DDR3/1333 module can be had for $35 right now, or roughly $4 a chip in retail. This puts DDR3 quite close in cost to GDDR3, and prices never tend to go up on memory.

The future according to AMD

Board makers can pick their poison, whichever is the lower cost part, use it. If you save a dollar or two here and there, you win a lot of sales. Consumers win too. This is the meat of the market, and a $5 end user cost matters a lot, and it matters more to OEMs. In addition to causing Nvidia a lot of headaches, it may just fatten the margins of the board makers by a point or two. Win/win, unless you are wearing green.

The MSRP of the 4670 is $79 with 512M of GDDR3, and there are both 1G and DDR3 variants coming as well. DDR2 versions list for $69, but lose a lot of performance. The take home message here is that the cheapest Nvidia 9500GT with GDDR3 is $77 with most of the others are $79-99, and the ATI card kill that part in all performance tests. It even beats many cards a few price notches up.

This is going to make life very hard for Nvidia, look for the rebates to flow and the margins to drop. Once you take retail pricing into account, the 4870s will likely lose $10 off the MSRP, putting them on the shelves against the much slower 9500GT/DDR2 parts. This is not a fair fight, but that is retail competition for you. The real damage here is going to be in the OEM market, where most of the sub $100 cards are sold. If you don't think $5 matters, go ask a Dell component buyer about economics for an ear full, they would kill for a tenth of that.

The launch of the 46xx series today is simply more of the same. It forces Nvidia to slash prices in an attempt to compete. The profits they were planning on making with their much ballyhooed 55nm transition likely just went up in the smoke of market pressure.

The same process that gutted Nvidia in the high end is now extended to the mid-range, with only one market, the low end left to fight over. It doesn't take a genius to realise there is still a hole in the 4xxx lineup, and the interesting summer isn't over yet. µ