AMD 790GX - The Introduction

by Gary Key on August 6, 2008 12:00 PM EST

We Need to Talk -

How about a short recap. The 790GX Northbridge is actually a 780G that has its stock core clock speed increased from 500MHz to 700MHz along with a graphics core name change from Radeon HD 3200 to HD 3300. Sideport Memory, now called Performance Cache, is a “requested” feature on the boards that improves IG performance about 5% on average, sometimes less, sometimes more. The SB750 Southbridge is basically a SB700 with RAID 5 operation and the new ACC interface. Mix the two parts, stir, and you have the highest performing integrated graphics solution on the market today.

However, the 8.521.1 driver set that enables all of this goodness is still beta and has a few warts that will be fixed very shortly. In addition, needed BIOS tuning by the various manufacturers is well underway. In fact, we have already received major BIOS updates today from each board supplier that at first pass have solved a multitude of problems we asked the manufacturers to address.  

Stock operation of the boards we are testing has been extremely stable, the majority of our problems that were not driver related occurred when overclocking the system or trying off-center combinations of components or settings. Our initial experiences lead us to believe that the release of the 790GX was about a week to ten days too early. However, our initial feedback to AMD and the motherboard suppliers have been addressed quickly and professionally. So much so, that we would not hesitate in purchasing this platform if it addresses your requirements.

 

Getting back to our original requests to AMD when asked what we would like to see in the next chipset. They addressed most of our requests from lower power consumption to improved IG performance. We ended up getting a bonus called Advanced Clock Calibration for our clock challenged Phenoms and a platform design that can run 140W TDP processors on a four-layer board.  

Our price point request of $100 to $135 is almost a reality. However, for the multimedia crowd, our passionate requests for multi-channel LPCM audio over HDMI will have to wait until the next product. In addition, we were let down about the 790GX being little more than an overclocked 780G. We originally thought this product was going to replace the 790FX by offering like performance and features plus an integrated graphics core. The jury is still out on improved performance but we do know the 790FX is going to remain as the lead performance chipset in AMD’s product lineup for the foreseeable future.

AMD is targeting this platform to both the enthusiast and multimedia user, which sounds like an oxymoron to us. For the multimedia user, spending additional money over the 780G for slightly higher clock speeds, performance cache, and the SB750 is going to be a hard sale for this market. Especially when 780G boards from J&W and Jetway already offer the performance cache and can easily reach 700MHz on the IG unit. The SB750 does offer ACC and along with it the opportunity to run lower voltages, not to mention a decent RAID 5 implementation.

For the performance crowd, the average price point of this board is in the right market unless the 790FX/SB750 boards arrive at or below the $150 mark. If that occurs, then we see a product that will be lost in the market unless AMD can implement something akin to HybridPower from NVIDIA, which allows the discrete card to power down and switch to the IG unit at idle for less demanding tasks like Office Applications or Bejeweled.  Otherwise, the IG unit and all of its potential benefits are wasted with a discrete card setup. 

That brings us to what we see as the jewel of this product release, the SB750. It brings sorely needed overclocking headroom for the underrated Phenom processor series via ACC, an additional RAID mode, improved AHCI performance and implementation, and it works with all current AMD Northbridges. We wonder if a two-product strategy with a 780G+/SB750 and 790FX/SB750 would have been a better marketing choice for AMD. That is the question we will answer in the next review.

It is warm and friendly down South...
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  • Janooo - Thursday, August 7, 2008 - link

    Gary,
    you could be right when you say:
    "Curiously enough, AMD cited "competitive concerns" as a reason why it would not disclose exactly what's going on with this new overclocking feature. We still cannot help but wonder if it is because AMD is going a little too far in the sacrifices, it is willing to make in the quest for higher clock speeds."

    Though, another reason could be that AMD found something nice that would give Intel even higher edge if they knew what AMD did.
  • ZootyGray - Thursday, August 7, 2008 - link

    "reason could be that AMD found something nice"

    Agree. And this same statement was uttered when ACC appeared in the SB750 review.

    I would like to know - WHAT is the sacrifice? The apparently unqualified statement seems to cast doubt and nasty slur, and really should be explained, methinks.
  • ET - Thursday, August 7, 2008 - link

    First of all, I'd like to say well done on letting us know of the issues and not rushing out a review like other sites. (Though I must say that having access to both fast and in depth reviews is the best of both worlds, so I'm also glad these other sites exist.)

    One thing which wasn't clear to me was: "vertex and texture caches are fully associative instead of separate." "Fully associative" has a meaning when it comes to caches, yet I imagine that's not what it's about. Sounds from the sentence like the caches have been unified (as opposed to separate).

    Since according to the text this is the only departure from the 2400's architecture, it'd be nice to clarify this point.
  • quanta - Wednesday, August 6, 2008 - link

    It seems the 'new' Advanced Clock Calibration is based on something that already existed in SB700 but was undocumented.[1] Based on the speculation, ACC could be the clock skew feature used by some other motherboards.

    That aside, RAID5 is a definite welcome addition, but unless it includes XOR offload, it really isn't much of an improvement. BTW, it is inexcusable for not having Ethernet support these days.

    The claim of adding 2 specific 1.1 ports for compatibility reasons is confusing. USB 2.0 ports are 1.1 already compatible, just using slower speeds.

    HyperFlash is a poorly implemented idea, especially when production Flash SSDs already exceed the maximum bandwidth of HyperFlash modules anyway. It is better off to just wait for Flash SSDs to mature.

    [1] http://www.overclockers.com/tips01369/">http://www.overclockers.com/tips01369/
  • Goty - Wednesday, August 6, 2008 - link

    It's possible, but I find it odd that a notoriously anti-AMD site (at least recently) like overclockers.com did absolutely no testing to confirm this hypothesis.
  • chucky2 - Wednesday, August 6, 2008 - link

    ...to please give us 690G results along with it, for the benchmarks and power consumption. This way, we can see if 780G and/or 790GX, or one of the other competing solutions, is a worthwhile upgrade for us. One of the Gigabyte 690G boards would be perfect...

    Chuck
  • ZootyGray - Thursday, August 7, 2008 - link

    And which manufacturer's 780G mobo would run with a Phenom 9950BE ? Is that possible?

    I am wondering how far the 780G comparison can go; since several mobos were destroyed back in April or May anand testing. (search The Three Amigos or "pop goes the mosfet"). Did the various manufacturers make any changes to replace the cheap mosfets they were using? 780G is a great N/B chip but some older(?) boards need lower-power cpu's. Other newer boards? - not sure yet. Still awaiting the update on all that. Did I miss something?
  • chucky2 - Thursday, August 7, 2008 - link

    So when the review comes out, use the maximum CPU that the 690G board supports, and carry that forward to the 780G and 790GX boards.

    Also it'd be nice to see the CPU comparison on like minimum CPU needed to play 1080p content.

    Also, best price/performance CPU out, cheapest dual core out, and older AM2 CPU's such as the 3600+ X2.

    Show us what we can expect when it's not a Phenom running in there, i.e. give us information users - both existing and new - would find helpful in the review.

    Chuck
  • yyrkoon - Wednesday, August 6, 2008 - link

    Lets just say that Stability is the main reason why I purchase what I purchase name brand wise. Motherboards, memory, and power supplies are my main concerns and probably will be for a long time to come.

    Anyways, performance numbers etc are always good to know also, but I think it would be good if you guys at anandtech could put some 'stability figures' in your motherboard results as well. "This board performed well ..." would not work for those of us who want to know actual figures either. So maybe you guys can include a page, half a page or something dedicated strictly to stability ?

    One of the main reasons why I am asking for this is as an example, I have an AM2 opteron system, as well as Core 2 Duo system, and while I love my AM2 system, and it *is* 'very stable', it still can not touch the rock solid stability of the Intel system. I do not pretend to know why, but I would love to figure out why . . . Both system have a board made by the same manufacturer, have used the same memory, video card(same company made both the GPU, and motherboard chipsets - nVidia)power supply, and hard drives. Hell, the Intel system has even been overclocked for 6-7 months now : /

    Going from the above I am left at guessing that it is either 1) a hardware implementation, or 2) drivers. User error *is* a possibility, but I would like to think that since I have been fixing / integrating systems since the early 90's . . . well that I at least know half of what I am doing. That said, this 'issue' is still over my head.
  • Calin - Thursday, August 7, 2008 - link

    It could be hardware implementation, it could be something that could be solved by a microcode/BIOS update, or maybe not. Also, there might be a difference between individual components (as similar as they are in theory), difference in general quality between the two mainboards, difference in component quality on boards (either by design or by chance/bad capacitors). It might be in the drivers, or just in things written in the processor errata which are not taken into account by the software.

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