Retesting the Radeon HD 4830: Too Few SIMDs Enabled
by Derek Wilson on October 25, 2008 12:00 AM EST- Posted in
- GPUs
So Why DID This Happen?
We asked, and AMD answered. They did not test the review samples before they sent them out to reviewers. We can usually expect to recieve boards that have not been fully QA'd, as that can take a while, but when ever we get new boards or software companies tend to make sure that what we are getting works right. Apparently AMD was in such a rush to get reviewers parts for launch that they didn't have time to run even a basic check after the cards came back from the factory (which ever company they use to build their reference boards).
So the answer is that they were in a hurry and assumed that the correct BIOS would be installed. It wasn't and they didn't catch it.
Now, apparently there were some review samples that had the correct BIOS on them. We aren't sure who received those samples, but AMD indicated that it was based on how early the sample was sent out. Those who got later batches were more likely to have boards with the correct BIOS.
So why won't this happen in the wild? Because AMD's board partners all QA the boards they sell and because they all had a different version of the BIOS (one that functioned correctly) from the beginning.
We've been doing this for a long time, and there are times where an engineering sample or some pre-alpha something or other will have major problems. The closer it is to ready the less disastrous the testing experience tends to be. Sometimes review hardware has big issues too, perhaps with power saving optimizations or fan control. We've have stability issues on plenty of review samples.
These type of problems tend to be easily noticable, and can usually be fixed or worked around. But we tend to know what's wrong (or even that there is something wrong). In most cases these issues are taken care of before hardware makes it into the hands of end users. In this case, there shouldn't be anything for end users to worry about either.
But this is still sort of a big deal. Not because it impacts the hardware people will buy, but because it invalidates the evaluations of many of the reviews that went live on launch day. You only get one chance to make a first impression, and the diminished performance from these errant review samples could leave a false impression on those who are most likely to keep up, read, and recommend graphics hardware.
We were softer on the Radeon 4830 than on the other RV7xx hardware we've reviewed. Yes, we still saw it as a part that offers a lot of value, but the price competition from NVIDIA has been heavy and there are more powerful cards that can be had for maybe $30 more with all the mail in rebates going around.
So what do we think now that we've seen the newly flashed Radeon HD 4830 in action? Well let's take a look at the numbers first.
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JAKra - Saturday, October 25, 2008 - link
Hi!I thought that these disabled SIMDs were fused off in the ASIC. What if you flash your HD4830 with an HD4850 BIOS or a modified one enabling all the SIMDs? The PCB looks the same, they use the same GPU.( I think )
Good old modding days are back: 9800SE to 9800XT, anyone? :D
Clauzii - Sunday, October 26, 2008 - link
Heh, I have that :D Still rockin' :DJAKra - Saturday, October 25, 2008 - link
Wehehe Marlin1975, you beat me to it. You won. :DDerekWilson - Saturday, October 25, 2008 - link
we'll have to look into that :-)Marlin1975 - Saturday, October 25, 2008 - link
Does this mean we might be able to just do a firmware flash and get a 4850 level performance??? :)Gary Key - Saturday, October 25, 2008 - link
I tried that on a retail card, no go.PrinceGaz - Saturday, October 25, 2008 - link
Did you down-clock the 4850 BIOS so that it was within the limits of the 4830 card? I'm thinking especially about the memory here which would be most likely to have problems at the 4850 clock-speed, unless you've already verified that your 4830 can run at the 4850 core and memory clocks. As an nVidia owner, I don't know what BIOS editing tools are available for AMD cards, but I doubt any have been tailored for the 4830 as it is brand new.Even if the 4830 could cope with 4850 clocks, there may well be other tiny but significant changes to the card components which mark it as a 4830 and prevent it being flashed with a 4850 BIOS. A modded 4830 BIOS with more than 8 blocks of 80 SIMDs enabled would therefore have the best chance of success, and may well be forthcoming now that AMD inadvertently made BIOSes with both 7 and 8 blocks enabled public, especially if combined with what can be ascertained from the 4850 BIOS. I wouldn't know where to start with BIOS editing (I can work with x86 assembly, but that is child's play compared to understanding proprietary BIOS code). Some people have produced utilities which can edit at least certain parameterrs in BIOS files, so it's possible a tool to select the number of SIMD blocks could be produced.
It's probably not worth the effort though as the 4850 is only slightly more expensive anyway, so even if you could up the SPs from 640 (8 blocks) to 800 (all 10 blocks), given the performance differences presented in this article by going from 560 (7 blocks) to 640 (8 blocks); you'd be lucky to add more than 10% at best-- and that's assuming your card actually has a core with all 10 blocks capable of working correctly. It's not like the good old days of the 9500 non-Pro which if you were lucky could have its pipelines upped from 4 to 8 (like a 9700 non-Pro) giving a staggering increase in performance.
It's obvious how AMD messed up with the card samples they sent out. The only possible explanation is that the 4830 was originally intended to have 560 SPs and the BIOS was designed with that limit. Late in development, serious price-drops of 9800GT cards and the like forced AMD to give their 4830 a bit extra umph to compete at the price-point they had already targeted it at. Whereas they could easily adjust any physical limitation of the hardware pretty much as it was leaving the fab if they do so (by disabling less blocks on those cores), it takes longer to modify the software and check it to a level they can be confident the card will actually function correctly, such that some review samples went out with the older BIOS.
As such, all 4830 card cores may well be limited to 8 functional blocks (including those samples sent out with a BIOS setting it to 7 blocks), but only AMD insiders would know.
Goty - Sunday, October 26, 2008 - link
Or maybe it was much less complex than that and AMD actually tried more than one configuration during testing and a batch slipped through the cracks once everything was finalized. Y'know, that whole Occam's Razor thing.iwodo - Saturday, October 25, 2008 - link
ATI deliberately sent out sample with worst results. Then give better bios for enabling proper performance to catch Nvidia Off Guard.SiliconDoc - Monday, January 19, 2009 - link
How about ATI did this because they are morons, the ATI division just caused another huge chargeout loss for AMD, so there's bad karma at ati , and this shows exactly why their drivers are so screwey and broken all over the place." We were in a hurry" - can you imagine ? Something as ignorant as the wrong bios applied - that really takes the cake.
Congratulations ati, you screwed up again - and no, your fanboys can't admit it, they think it's a masterous marketing plan to destroy nvidia...
ATI blew it again.
( They did do very well on this card though, it's the first one at the pricepoint it's at that I like from them - since there's no CUDA, no PhysX, no driver profiles, a bloated CCC bloated a bit less, - no I don't plan on picking one up. )
Yeah, despite the major, amatuer, almost laughable mistake - makes ya wonder if anyone is at home or in charge there, this is a nice card for the price right now.