AMD K6-3 ???

[Scojo]

What happened to all of AMDs K6-3 450s? There are plenty of K6-2s out there and finding an athlon isn't a problem. I'm trying to squeeze the last bit of life out of my socket 7 setup and put off getting a slot A.

Thanks,

Scott

[ramashiva]

Basically, there are no more k6-III processors available, although Spartan Technologies at http://www.spartantech.com/ is currently listing 400 mhz k6-III processors for $142. I don't know if these are 2.2 or 2.4 volt processors. I bought one of the 2.4 volt units last year for $65 and was able to stably overclock it to 448 mhz (4x112) at 2.8 volts.

I was fortunate enough to buy a genuine 500 mhz k6-III a few months ago from the same company for $199. This is a beautiful chip. It runs completely stable at 504 mhz (4.5x112) at 2.2 volts, proving it is a genuine 500 mhz processor. As you probably know, 450 mhz processors have to be pushed to 2.8+ volts to reach 500 mhz. k6-III processors just cannot be overclocked to any great extent.

It's too bad AMD never released the k6-III+ (.18 micron versus .25 micron), because that would be a killer CPU and quite overclockable. Of course, the real reason AMD never released this beast is because it would have blown the doors off the pre-thunderbird athlon and the pre-coppermine pentium III. Clock for clock the k6-III was simply the fastest processor around until the thunderbird and coppermine processors were released. At 504 mhz my k6-III scores 52+ on CPUmark 99. Check out what "classic" pentium III and athlon processors score at 500 mhz. My 448 mhz CPU posted one of the fastest DOOM benchmarks ever using an ATI All-in-Wonder Pro!!! You can check the DOOM benchmark page at http://www.complang.tuwien.ac.at/misc/doombench.html.

At this point, your best bet to upgrade a socket 7 motherboard is the k6-2+. AMD has only released this CPU as a mobile version, and it only has 128k level 2 cache, compared to 256k for the k6-III. But it is a .18 micron CPU and apparently very overclockable. There are some issues about which motherboards will support this processor. Basically, you need a motherboard which can set the voltage to 1.8 volts, or at least 2.0 volts; and your BIOS needs to recognize the k6-2+ processor.

There are in-depth articles on Ace's Hardware at http://www.aceshardware.com/ and Tom's Hardware at http://www.tomshardware.com/ about the k6-2+. Vega Computer Industries at http://www.vegapc.com/ is currently selling 500 mhz k6-2+ processors for $89. This CPU should easily overclock to 600+ mhz, making it comparable to a 500 mhz k6-III.

[BlueScreen]

I agree with ramashiva, a K6 2+ or 3+ is the way to go if you are trying to stretch the life of a Socket 7 System.

It is possible to buy K6 3+ CPU's !!!!

They have "leaked" onto the market in Australia and I am a very happy user of one. There is only 1 known source that lists on the web:
http://www.auspcmarket.com.au/
They don't take overseas credit cards so you need to be keen to put up with the hassles. They also appear on "over the counter" sales at PC fairs etc in Sydney.

My k6 3+ runs rock steady at 600 meg (although rated at 450!) without upping voltage. It will also run at 617 but my PC config is not so happy, memory , PCI issues cause one or two problems a week so I stay at 600. These occur with 112 FSB irrespective of CPU used or CPU speed, so they are PC specific. Given a better system the K63+ I'm using would be stable at 617.

Benchmarks are good, I get arround 55 on CPU mark 99 and Sandra benchmarks are comparable with similar clocked Celeron or P3's. The only weakness is memory is still low but I'm currently working on finding the optimum bios "tweaks" to maximise this. 3dmark is 3300 with a GeForce 1 DDR, which is ok for a SS7 system and makes even demanding games playable and smooth with sensible settings.

The AMDZone forum has several threads that may be of interest, look at:
http://www.amdzone.com/forum/categories.cfm?catid=13

Most K62+ and 3+ users who have posted results seem to get to 600 without many problems so either cpu is a good choice. Most but not all MotherBoards can be made to work with either a BIOS update or software tools to enable write combining and other CPU features that are normally turned on by the BIOS.

Good Luck.

Greetings from "Olympics City"

[ramashiva]

I am very excited by BlueScreen's post revealing a supply source for k6-III+ processors. I can hardly wait to get my hands on one of these bad boys.

Meanwhile, I would like to share my experiences overclocking and tweaking my current CPU, a 500 mhz k6-III which I have running rock solid at 504 mhz (4.5x112) at 2.2 volts on a FIC VA-503A motherboard using a 128 mb stick of EMS ECC HSDRAM. This memory module is conservatively rated at CAS 3 at 133 mhz, although many internet reviews say it runs rock solid at 133 mhz at CAS 2, and at 150+ mhz at CAS 3. At 112 mhz I have this memory running with turbo BIOS settings, CAS 2, and zero wait-states. I can set the memory bus to 124 mhz and everything is still rock solid with the same BIOS settings.

The CPU is cooled by a cool-it-dude 40-watt peltier cooler from Computer Nerd. Under full load, the CPU temperature rarely exceeds 22 degrees C., and the two system chips run at about 25 degrees C. and 30 degrees C.

My previous CPU was a 2.4 volt 400 mhz k6-III. I had to struggle to get this processor to run stably at 448 mhz (4x112). Initially, I had to crank the voltage all the way up to 3.0 volts, and the CPU still crashed fairly frequently. After a burn-in period, the crashes stopped and I achieved stable operation at 2.8 volts.

Imagine how thrilled I was when my new 500 mhz CPU ran rock solid at 504 mhz at 2.2 volts right out of the box. I thought "This baby is going to hit 600 mhz without breaking a sweat." Unfortunately, this has not been the case, and I have been unable to achieve stable operation above 504 mhz.

I'm not sure if the limiting factor is the CPU, the motherboard, or the cooling. I'm pretty sure the HSDRAM is not the problem.

For those of you not familiar with the FIC VA-503A motherboard, a few important facts --

1. The motherboard is based on the VIA MVP3 chipset.

2. The motherboard has dipswitches to set CPU clock multiplier, voltage, and memory-bus speed.

3. The CPU front-side bus (FSB) speed defaults to the memory-bus speed, but can be independently set in the BIOS to 100 mhz, 112 mhz, or 124 mhz, regardless of memory-bus speed.

4. There is a special dipswitch setting which sets the memory-bus speed to 83 mhz and the FSB speed to 124 mhz. This setting is mainly for slower SDRAM (PC 66) which cannot handle 100+ mhz bus speeds.

All righty, then. When I set the CPU for 560 mhz (5x112) operation, it will POST just fine at 2.6 volts, but always crashes somewhere during the Windows 98 boot process. Upping the voltage as high as 3.0 volts does not correct the problem. Similar results are obtained at 550 mhz (5.5x100). As I said before, I don't know if this a CPU limitation, or if I need more cooling (such as a 78-watt Swiftech peltier), or a different motherboard.

The second frustration I have experienced is that I the only way I can get 124 mhz FSB speed is to use the special dipswitch setting which sets the memory-bus speed to 83 mhz. With this setting, everything works fine at 496 mhz (4x124). But if I set the memory-bus speed to 100 mhz, 112 mhz, or 124 mhz, the clock multiplier to 4, and the FSB speed in the BIOS to 124 mhz, the system will not even POST.

By the way, I have no problem setting the memory-bus speed to 124 mhz, as long as the FSB speed setting in the BIOS is 100 mhz or 112 mhz. Is this bizarre or what???

Has anybody had any success running any MVP3-based motherboard with both the memory bus and FSB running above 112 mhz? Yes, I know the Ali V based boards have this capability, but the Ali motherboards do not support ECC above 100 mhz. As far as I'm concerned, using non-ECC memory is pure insanity. ECC memory is only a little more expensive, and it gives you a definitive hardware check on the integrity of retrieval of information from system memory.

The Ali V chipset also provides better memory bandwidth than the MVP chipset, about 200+ mb/sec versus 150+ mb/second, as measured by SANDRA. Memory bandwidth is a weakness of all Socket 7 chipsets. I'm getting 160+ mb/sec on my current system, and can get up to 180+ mb/sec by tweaking all the BIOS memory settings aggressively with TWEAKBIOS.

I'm sure I could get a substantial boost in memory bandwidth by enabling 4-way interleaving. All 128 mb memory modules have four banks, so this would not be a problem. Unfortunately, my BIOS does not have settings for memory-bank interleaving, and, strangely enough, neither does TWEAKBIOS. I don't understand this, because I'm sure the MVP3 chipset supports memory-bank interleaving because the EPOX MVP3G series of motherboards have this setting in their BIOS. Oddly enough, so does the FIC VA-503+, the predecessor to the FIC VA-503A.

DOES ANYBODY KNOW OF A WAY TO ENABLE MEMORY-BANK INTERLEAVING ON MVP3 MOTHERBOARDS WHICH DON'T HAVE SUCH A SETTING IN THE BIOS???

Speaking of the EPOX MVP3G motherboards, they are the most likely candidate for me to get my k6-III to 560 mhz or higher. Supposedly, the original MVP3G-M (1 mb cache) is the fastest, as the memory settings on the MVP3G-2 (1 mb cache) and MVP3G-5 (2 mb cache) are more conservative to increase stability. Also, the MVP3G-5 supposedly has inferior tag ram, which supports the motherboard cache, and which makes stable operation at bus speeds above 100 mhz difficult or impossible. I would appreciate hearing from any MVP3G motherboard owners who have any definitive information on these supposed facts. More importantly --

HAS ANY EPOX MVP3G MOTHERBOARD OWNER BEEN ABLE TO RUN A K6-III AT 560+ MHZ, AND/OR ACHIEVE STABLE OPERATION WITH BOTH MEMORY BUS AND FSB RUNNING AT 124 MHZ?

SAME QUESTION FOR ANY OWNER OF A FIC VA-503A MOTHERBOARD OR ANY OTHER MVP3-BASED MOTHERBOARD.

A final note on k6-III performance --

It is important to enable both write allocate and write combining for optimum performance. If your BIOS doesn't have settings for these features, there are many utilities on the internet available for free download which enable these functions. If you can't find these utilities, and/or can't figure out how to use them, send me an e-mail and I'll give you some hints.

[ramashiva]

In my previous post, "amd k6-III overclocking and performance issues", I stated that I could set the memory-bus speed to 124 mhz on my FIC VA-503A motherboard. That is true, but I neglected to mention that a couple of tweaks were necessary to achieve stable operation at 124 mhz.

First, I had to raise the CPU voltage from 2.2 volts to 2.6 volts to get the system to POST. Strange, you say? I thought so, too. If you recall, I'm running my k6-III at 504 mhz (4.5x112). That's a clock multiplier of 4.5 and a FSB speed of 112 mhz. The CPU is very stable at this speed at 2.2 volts, which is its rated voltage. But the FSB speed of 112 mhz is a BIOS setting. When the system begins the POST operation, apparently the dipswitch settings for clock multiplier and memory-bus speed are the determining factors. So I have to supply the CPU with enough voltage to run at 4.5 x 124 mhz = 558 mhz. That voltage requirement is 2.6 volts.

Second, I had to disable spread spectrum modulation. This setting is located in the BIOS under the Chipset Features Setup heading. I am pretty sure disabling spread spectrum modulation will increase memory stability on any motherboard at memory-bus speeds above 100 mhz.

I think it is safe to generalize that, on any MVP3-based motherboard, if you set the FSB speed in the BIOS below the memory-bus speed set by jumpers or dipswitches, then you must supply the CPU with sufficient voltage to POST at the product of the clock multiplier and the memory-bus speed.

Running my memory bus at 124 mhz results in slight, but measurable increases in CPU performance and memory bandwidth. However, I have chosen to run my memory bus at 112 mhz so I can keep the voltage set at 2.2 volts. I'm pretty sure cranking up the voltage on any CPU shortens the trouble-free life of that CPU, even when well-cooled. I'm willing to sacrifice CPU life for a better overclock, but not for marginally better SANDRA scores.

[Scojo]

Thanks for the info, fellas.

Thanks,

Scott

[BlueScreen]

Ramashiva,

Yes you can use memory interleaving etc even if you Bios does not have a setting. I've done this and gained around 20% with the system being noticably faster.

Take a look at :

http://viahardware.com/memtweakguide1.htm

WPCREDIT and WPCRSET are not very intuitive but with care you can set any features that the chipset supports. Overall I can get up to 40% improvement in memory benchmarks but end up with instability. It takes many weeks to test each option with a solid overnight stability test for each one.

As you sound like a "compulsive tweaker" (as I am) these tools will keep you happy for many months !

It is also a good Idea to donwload the chipset specs from VIA as then you have full details of all parameters you can use.

Good Luck


NB Apologies to anyone anoyed that this thread is not in the correct place.