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Unlocking & Overclocking The AMD Slot A Thunderbird
Date: Dec 14, 2001
Author: HH Editor
Unlocking & Overclocking The AMD Slot A Thunderbird - Page 1

Unlocking & Overclocking The AMD Slot A Thunderbird
Straddling the fence between the old and the new

July 4, 2000 - By Dave Altavilla 

In this weeks installment of "my PC is faster than yours", we have a new processor that has emerged in the High End space.  AMD's long awaited Thunderbird (god I love that code name) has arrived and it's sporting 256K of on chip full speed L2 Cache.  Along with this new CPU, we will be using a new motherboard from Gigabyte, the GA-7VX (full review coming soon), designed around VIA's new KX133 chipset affording AGP4X and PC133 memory support to the Athlon platform.  The combination of this new round of technology from the two primary Intel competitors, has painted a landscape of options for the end user. 

This is a HotHardware evaluation and a project of sorts, with two very mainstream products in the AMD platform.  We are pairing the Gigabyte GA-7VX with the AMD Thunderbird Athlon 700MHz. Processor.  Both of these products are very reasonably priced and should be as much of an "average" users configuration as any mid range Intel base platform on the market.  We'll look at the features and performance.  Then, just for the "fun factor", we'll over-clock the stuffing out of it (no Vapochill here, just standard equipment) to see what it will do.  In addition, there are some subtle nuances you need to be careful of with any new architecture.  More on this later.

We would like to start this review off right by giving thanks to our good buds over at Azzo Computers for hooking us up with the T-Bird 700.  We don't make to many recommendations around here, on where the best places are to buy your hardware but when we do, they have to be top notch people to get our plug.  Azzo is definitely one of those places.   

Now, let's look at our setup.

Specifications Of The Bird
Cold Hard Cache

Historically, the Athlon core was populated on a multi chip printed circuit board for the Slot A configuration.  The SRAM L2 Cache was installed on the CPU Module discretely.  This allowed for a large cache size but slower access times and getting on and off the CPU core to access that cache was slower than the integrated solution of today.

Look Ma!  No SRAM chips! (click image)

This is an image of the new Athlon that AMD code named "Thunderbird".  As you can see in this shot, there are no SRAM chips on the PCB.  All of the T-Bird's SRAM cache is now on chip and running at full speed with the processor.  You may have already seen the Socket A version of the T-Bird which is set up for a 462 Pin Grid Socket.  In the event you haven't yet, here is what this chips looks like.

Just keep in mind that we will be taking a look at the SLOT A version of this chip, as shown in the top shot.  This will be important to remember later on in our tests.  Here are the rest of the specifics for the T-Bird.  Both chips have the same electrical specs with the exception of the form, factor obviously.

  • Multiple parallel x86 instruction decoders

  • Three out-of-order, superscalar, fully pipelined floating point execution units, which execute x87 (floating point), MMX? and 3DNow!? instructions

  • Three out-of-order, superscalar, pipelined integer units

  • Three out-of-order, superscalar, pipelined address calculation units

  • 72-entry instruction control unit

  • Advanced dynamic branch prediction

  • Enhanced 3DNow!? technology for leading-edge 3D performance

  • 21 original 3DNow! instructions-the first technology enabling superscalar SIMD

  • 19 new instructions to enable improved integer math calculations for speech or video encoding and improved data movement for Internet plug-ins and other streaming applications

  • 5 new DSP instructions to improve soft modem, soft ADSL, Dolby Digital surround sound, and MP3 applications

  • Compatible with Windows® 98, Windows 95, and Windows NT® 4.x without software patches

  • 200MHz AMD Athlon? system bus enabling leading-edge system bandwidth for data movement-intensive applications

  • Source synchronous clocking (clock forwarding) technology

  • Support for 8-bit ECC for data bus integrity

  • Peak bandwidth of 1.6 to 3.2 GB/s

  • Multiprocessing support: point-to-point topology, with number of processors in SMP systems determined by chipset implementation

  • Support for 24 outstanding transactions per processor

  • 128K of L1 cache and 256K of integrated, on-chip L2 cache for a total of 384K full speed, on-chip cache

  • Slot A - Available in processor cartridge with mechanical dimensions comparable to Pentium® III.  Leverages existing physical/mechanical Slot 1 PC infrastructure, including mechanical connector, but with different bus protocols and electrical definitions

  • Electrical interface compatible with 200MHz AMD Athlon system bus, based on Alpha EV6 bus protocol

  • Socket A - Available in Pin Grid Array (PGA) for mounting in a socketed infrastructure
    Electrical interface compatible with 200MHz AMD Athlon system bus, based on Alpha EV6? bus protocol

  • Die size: approximately 37 million transistors on 120 mm2 die on 0.18-micron process technology

If you look at this architecture from a "specsmanship" standpoint, one would have to admit that AMD has Intel beaten for the most advanced architecture in PC processors right now, at least for what is available on the market today.  Again, the two main strong points here are that the internal system bus runs at 200MHz. and the on chip cache is running at full speed with the processor.  The later of the two bullets is something that Intel has had since the earlier days of the P3 and it is why AMD lagged slightly in performance on some applications, until now.  Finally, there is also support for Multi-Processor systems although there are no motherboards or chipsets shipping currently that support it.

So, in an effort not to bore you with an over-abundance of technical detail, let's plug our new "Winged Bird" in and hit the power button.

Installation, Setup, stability  and Overclocking


Unlocking & Overclocking The AMD Slot A Thunderbird - Page 2

Unlocking & Overclocking The AMD Slot A Thunderbird
Straddling the fence between the old and the new

July 4, 2000 - By Dave Altavilla

HotHardware's T-Bird Test System
A little un-orthodox

Full Tower ATX Case w/ 300W PS,  Slot A Thunderbird Athlon 700 (provided by Azzo Computer), Gigabyte GA-7VX (full review soon), 128MB of PC133 SDRAM, WD Expert AC418000 7200 RPM ATA66 Hard Drive, Elsa Gladiac, Kenwood 72X CDROM, Win 98SE,
NVidia 5.30 Drivers, DirectX 7.0a

Installation / Setup On A KX133 Board
Not "fully supported" but...

Alright then, let's get something out in the open here.  The Slot A Thunderbird Athlon from AMD is a chip that quite frankly isn't supposed to be in the reseller channel.  However, the crafty folks at Azzo Computer, as well as a few other on line retailers, have gotten a hold a these chips and are making them available for sale as long as supplies last.  AMD is really only manufacturing the Slot A version of the chips for certain OEMs that have Slot A motherboard designs still in the production flow.  The Socket A version is intended for the R.O.W. (rest of the world) demand and there are currently several motherboards released based on the VIA KT133 chipset which support this socketed version.  Now, having said this, the only currently shipping Slot A chipset that "officially" supports the Slot A T-Bird, is the AMD 750.  The current version of the Slot A chipset from VIA, the KX133, only "officially" supports the older version of the Athlon with discrete cache on the PCB. 

With this in mind, you are probably thinking, "why take one step forward to go one step back"?  For the users out there who are currently running a motherboard based on the AMD 750 chipset, the Slot A Thunderbird will provide new levels of performance with just a drop in solution.  For those users who are looking at an entire new platform however, you would be hard pressed to opt for the AMD 750 based boards on the market when the VIA chipset based solutions provide the PC133 Memory and AGP 4X support that the 750 doesn't have.  So, where does this leave the Slot A?  Well, frankly somewhere in between the old PC100 and the new PC133 platform for the Athlon.

HOWEVER, we decided to see what would happen when we tried to setup the Slot A T-Bird on a KX133 board.  We were pleasantly surprised to see that indeed it did run and was stable.  In our tests, we used a new Gigabyte KX133 board, the GA-7VX.  It supports all of the usual features of the KX133, including ATA66, AGP4X, PC133 Memory and PC Health Monitoring. 

We'll have a full review of this board shortly but for now here is the obligatory "candid photo"....

(click for larger image)

Again, more on this board when our boy "BigWop", delves into it with a full review.  However, suffice it to say that Gigabyte has some of the most stable motherboards on the planet in our opinion.  They may not always have the widest assortment of features but the quality is definitely in there.  Again this board was stable with our 700MHz. Slot A T-bird at stock speed and with a little bit of over-clocking.  We want to be very specific here however, again this chipset does not "officially" support the T-Bird, at least for now.  Your experience with a KX133 board and a Slot A T-Bird depends on many factors including among other things, a robust and clean power source.  We used a Power Man 300 Watt unit and it did the job nicely.

In addition, we have heard from one very popular and large Motherboard Manufacturer that they are working on a BIOS revision for their current KX133 Slot A board, which should bring full stability to the mix.  As soon as we get details on this, we'll let you know.  This could be VERY good those of us looking to "unlock" the T-Bird since the easiest way is with a GFD (Gold Finger Device) on a Slot A version CPU.

So, with that lead in, let's take a look at the over-clocking side of things shall we?

Overclocking The Slot A Thunderbird
Just like any other Athlon

We have good news for those of you who are not shy to crack open the case of an Athlon, exposing the "Gold Fingers" on top of the PCB.  The Outside Loop Afterburner DOES work with the new Slot A T-Birds.  It works exactly as the standard Athlon does and we were able to change the multiplier with it. 


On the top left of the PCB, you can see the Gold Fingers.  We also used a rather large Global Win Heat Sink and Fan combo with decent thermal paste joining the two.  On the right is the full setup with the Afterburner installed. We used the GA-7VX Motherboard's ability to change the Front Side Bus speed and dialed in stable at 115MHz. FSB.  The Afterburner allowed us to run at a multiplier of 7.5, only a half step higher than the stock multiplier.  However, this was the highest speed at which the processor would run stable with our standard mainstream cooling solution.  The voltage was dialed in to 1.85V which seemed the best level for stability.   

Now, in summary, I think we were fairly successful here with our Slot A T-Bird, in the over-clocking department.  From what we have seen of early Socket A T-Bird reviews, with the current multiplier lock (operative word is "current" here), they are only able to over-clock to about 10% over their stock speed since front side bus speeds over 115MHz. tend to bring out the "flakies" on the Athlon's EV6 bus type.  Our processor's native clock speed of 700MHz. was exceeded by almost 20% to a high of 863MHz.

For now, the only "unlocked" T-Birds will be the Slot A version.  We have heard of one motherboard manufacturer that is claiming to have unlocked the Socket A chips with specific pins that AMD designates for the multiplier.  We are making an effort to get a hold of one of these boards, when they are available and will keep you posted.

So, now that we have covered the basics here.  Let's dig in deeper on the performance side of things!


Benchmarks With The Unlocked T-Bird


Unlocking & Overclocking The AMD Slot A Thunderbird - Page 3

Unlocking & Overclocking The AMD Slot A Thunderbird
Straddling the fence between the old and the new

July 4, 2000 - By Dave Altavilla

HotHardware's T-Bird Test System
A little un-orthodox

System 1:
Full Tower ATX Case w/ 300W PS,  Slot A Thunderbird Athlon 700 (provided by Azzo Computer), Gigabyte GA-7VX Motherboard (full review soon), 128MB of PC133 SDRAM, WD Expert AC418000 7200 RPM ATA66 Hard Drive, Elsa Gladiac, Kenwood 72X CDROM, Win 98SE,
NVidia 5.30 Drivers, DirectX 7.0a
System 2:
Full Tower Tower ATX Case w/ 300W PS, Engineering Sample of Pentium III 933EB,  Abit CX6 i820 Motherboard,  128MB of  800MHz (400MHz. DDR) RDRAM, WD Expert AC418000 7200 RPM ATA66 Hard Drive, Kenwood 72X CDROM, Elsa Gladiac GeForce2 GTS AGP, NVidia GeForce Reference Drivers Version 5.30, DirectX 7.0a, Win98SE

Benchmarks On A Bird
Throttle up!

Let's just punch this one out so we can get to the fun.

Winbench 99 Test - @ 863MHz.

(click to view)

In the CPU and FPU Winmarks department, the T-Bird is right on par with our test system 2 at 933MHz.  Again, the KX133 and Thunderbird combination shows its muscle.


Finally, here are our obligatory gaming test scores with Quake 3 Arena.  What benchmarking test would be complete without it?  First, let's look at our system with no over-clocking to the CPU or Graphics Card.

Quake 3 Arena Timedemo

Not too shabby at all if you ask us!  But wait, let's turn it up a notch on both ends of the graphics pipeline!

For a processor that retails right around $200 (at Azzo, of course) you can't go wrong with this type of performance.  What is a little odd is the fact that the Graphics Card cost significantly more than the host processor in our system. 


Well, that just about covers all we know to date about the 700MHz. Slot A Thunderbird Athlon Processor.  We've shown you performance at all levels of clock speeds we could wring out of this new beast and how to run it on the latest chipset for the Athlon platform.  In the coming weeks, we feel fairly confident that the Slot A Thunderbird will make its way a little more to the mainstream channel and further stabilize on KX133 chipset boards.  If this happens, Power Users and Overclocking Fanatics around the globe will most likely flock to this chip for its value and better flexibility for over-clocking and unlocking the multiplier.  It will be interesting to see if the Socket A versions of the Duron and T-Bird chips start having their multipliers unlocked by the various Motherboard Manufacturers who are bold enough to add it as a feature.  Until that time, the Slot A T-Bird brings you its new high speed on chip cache with a little of the old Athlon accessibility through its "Gold Finger" connector.  We'll be dropping hints to various Motherboard Manufacturers urging them to stablize their KX133 boards with the Slot A Thunderbird.  We'll just have to see how the whole thing pans out.

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