Can/should I replace my old AMD K6 300 with a used K6-2?

[Robert Corrigan]

I'm trying to get some life out of an old (c.1998) PC.

It has an AMD K6 Model 7 @ 300MHz (BIOS detects AMD K6/300).
The motherboard is a PCChips M573 (TXPRO-III/VXPro+/VIA Apollo VPX
Chipset).
The BIOS is 4/30/1998 S which is the latest release I have found.
Memory is 64MB EDO 5V non-parity, tin connectors, in two SIMM slots.

Available jumpers on the motherboard:

CPU Core Voltage: 3.5, 3.3, 3.2, 2.9, 2.8, 2.5, or 2.2
CPU Type: P55C (dual-voltage) or P54C (single-voltage)
DIMM Voltage: 5.0 or 3.3
PCI Clock Speed: half-CPU or constant 33Mhz (must be 33 if CPU speed
is >=75)
CPU Speed Jumpers: 50, 55, 60, 66, 75, or 83
K6 CPU Multipliers: 2.5, 3.0, 3.5, 4.0, 4.5, reserved

The reserved multiplier is a 2.0X setting which the manual lists as
"reserved" for AMD chips. I have read that the K6-2 interpreted this
setting as 6X.

So can I replace the K6-300 with a K6-2 running at 400 (66*6), 450
(75*6), or 500Mhz (83*6)? Or is there some other limiting factor on
the board which would prevent me from doing this?

Data I have found while researching this indicates the TXPRO-III
supported 66Mhz and 75Mhz bus speeds and "unofficially" supported
83Mhz. I believe I'm at 66*4.5 now. But the K6-2 only supports 66Mhz
and 100Mhz bus speeds, so am I limited to 400Mhz? In that case, maybe
another Socket 7 CPU would be better?

I assume I'd need a new CPU fan to remove the additional heat no
matter what I choose.

Thanks for any advice.
RobertC

 

[philo]

I'm trying to get some life out of an old (c.1998) PC.

It has an AMD K6 Model 7 @ 300MHz (BIOS detects AMD K6/300).
The motherboard is a PCChips M573 (TXPRO-III/VXPro+/VIA Apollo VPX
Chipset).
The BIOS is 4/30/1998 S which is the latest release I have found.
Memory is 64MB EDO 5V non-parity, tin connectors, in two SIMM slots.

Available jumpers on the motherboard:

CPU Core Voltage: 3.5, 3.3, 3.2, 2.9, 2.8, 2.5, or 2.2
CPU Type: P55C (dual-voltage) or P54C (single-voltage)
DIMM Voltage: 5.0 or 3.3
PCI Clock Speed: half-CPU or constant 33Mhz (must be 33 if CPU speed
is >=75)
CPU Speed Jumpers: 50, 55, 60, 66, 75, or 83
K6 CPU Multipliers: 2.5, 3.0, 3.5, 4.0, 4.5, reserved

The reserved multiplier is a 2.0X setting which the manual lists as
"reserved" for AMD chips. I have read that the K6-2 interpreted this
setting as 6X.

So can I replace the K6-300 with a K6-2 running at 400 (66*6), 450
(75*6), or 500Mhz (83*6)? Or is there some other limiting factor on
the board which would prevent me from doing this?

Data I have found while researching this indicates the TXPRO-III
supported 66Mhz and 75Mhz bus speeds and "unofficially" supported
83Mhz. I believe I'm at 66*4.5 now. But the K6-2 only supports 66Mhz
and 100Mhz bus speeds, so am I limited to 400Mhz? In that case, maybe
another Socket 7 CPU would be better?

I assume I'd need a new CPU fan to remove the additional heat no
matter what I choose.

if you can get a faster cpu at a low price...it would help a little bit
but probably would not be dramatic...
your present heastink might be sufficient
you can always use a utility such as speed fan to check your cpu temp

55C or lower should present no problems at all
but i would not let it go past 60C



however if you added more RAM you might do even better

128 would be nice

 

[Nate]

On Wed, 11 Feb 2004 14:17:35 -0800, Robert Corrigan wrote:

Hey Robert,

I'm trying to get some life out of an old (c.1998) PC.

Sounds like a good plan to me.

It has an AMD K6 Model 7 @ 300MHz (BIOS detects AMD K6/300). The
motherboard is a PCChips M573 (TXPRO-III/VXPro+/VIA Apollo VPX Chipset).
The BIOS is 4/30/1998 S which is the latest release I have found. Memory
is 64MB EDO 5V non-parity, tin connectors, in two SIMM slots.

Ugh, PCChips... : P
Is that computer currently stable? I ran an Amptron (equal to PCChips)
socket 7 board in early '98 and had more trouble with that damn thing than
it was worth!

Available jumpers on the motherboard:

CPU Core Voltage: 3.5, 3.3, 3.2, 2.9, 2.8, 2.5, or 2.2 CPU Type: P55C
(dual-voltage) or P54C (single-voltage) DIMM Voltage: 5.0 or 3.3 PCI
Clock Speed: half-CPU or constant 33Mhz (must be 33 if CPU speed is
CPU Speed Jumpers: 50, 55, 60, 66, 75, or 83 K6 CPU Multipliers: 2.5,
3.0, 3.5, 4.0, 4.5, reserved

The reserved multiplier is a 2.0X setting which the manual lists as
"reserved" for AMD chips. I have read that the K6-2 interpreted this
setting as 6X.

Indeed they do.

So can I replace the K6-300 with a K6-2 running at 400 (66*6), 450
(75*6), or 500Mhz (83*6)? Or is there some other limiting factor on the
board which would prevent me from doing this?

Sure, I doubt you'd have much trouble running a faster K6 on that board.

Data I have found while researching this indicates the TXPRO-III
supported 66Mhz and 75Mhz bus speeds and "unofficially" supported 83Mhz.
I believe I'm at 66*4.5 now. But the K6-2 only supports 66Mhz and 100Mhz
bus speeds, so am I limited to 400Mhz? In that case, maybe another
Socket 7 CPU would be better?

Na, I think your best option is to stay with AMD's K6x series. IIRC The
K62 and newer processors only “officially†support 66, 95 and 100Mhz
FSB's, but they will run fine at other speeds. I've got a K62 333 running
on a 75Mhz bus (4.5x75) on an FIC-PA2007. A friend is using that computer
currently and has no idea the FSB is “out of specâ€, he just runs the
heck out of it and it's perfectly stable. I've also run a few K6x's on a
112Mhz FSB on an Epox EP-MVP3G5 back in the day and they were fast (for
their time) and stable. The only speed you may have trouble with is 83Mhz,
depending on how well the motherboard and chipset can handle it.

I assume I'd need a new CPU fan to remove the additional heat no matter
what I choose.

Maybe, maybe not. If you've got a decent heat sink now you will probably
be fine. If you're concerned about heat though you may want to look a
socket 370 or socket A heat sink. You'd have to check before hand to make
sure the HSF you choose will clip on a socket 7 board. I'd imagine most
modern, relatively low performance, quiet HSF's would work great on a K6.

As for a new CPU for your PC I'd look for a K62+ 500 or K6III+ 450 first
or perhaps a K6III at 400 or 450Mhz, failing that I'd go with a K62 500.

The 'plus' series are mobile chips and are fairly rare, but they are
excellent overclockers thanks to their being manufactured on an .18 micron
process rather than the .25 micron process of non-plus K62's and K6III's.
They also run cooler because of their .18 micron design which may be more
beneficial to you as you likely can't go faster than about 500Mhz with
your motherboard anyway. They also have the same extended 3DNow!
instruction set that the Athlon's do and most importantly they have full
speed, on-die L2 cache (128K for the K62+ and 256K for the K6III+).

The regular K6III's are also somewhat rare and probably expensive to buy
now. They have 256K of L2 cache also which really helps their performance,
but are difficult to overclock. Obviously that's not a problem if you plan
on running stock speed though.

As for the K62 500, it is probably the easiest to find and probably will
be the least expensive also. In fact www.newegg.com has them for $17
shipped right now. However, it has no advantage over your current CPU
other than clock speed.

Any of the above processors will run at speeds below what they were
designed for, they also will all run on all of the available bus speeds
you have. If you try a certain bus speed and find it's not stable then
your problem likely lies elsewhere in the system.

Thanks for any advice.
RobertC

No problem, hopefully it's useful. : )

Good Luck,
Nate

 

[Robert Corrigan]

(snip)

if you can get a faster cpu at a low price...it would help a little bit
but probably would not be dramatic...
your present heastink might be sufficient
you can always use a utility such as speed fan to check your cpu temp

Checked out SpeedFan; thanks for the tip. I'll definitely use it.

55C or lower should present no problems at all
but i would not let it go past 60C



however if you added more RAM you might do even better

128 would be nice

A memory upgrade is definitely planned regardless of the CPU upgrade.
I've been trolling eBay for the last couple days looking for an
additional 64MB... people keep overbidding me at the last moment... if
I find a good Buy It Now offer I'll likely snap it up.

Thanks again,
RobertC

 

[Biff]

You need to have a motherboard/bios that will support the "plus" chips
in order to run them. Here is a link that will give you the scoop on
that:
http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm

Also, not all K6-2 chips re-map the 2x multiplier to 6x. The re-map
feature is found on all K6-2s of 400 MHz or higher, and on all K6-2s
manufactured after Nov. 1998. The chips that have this feature are
known as CXT cores.

 

[Robert Corrigan]

Ugh, PCChips... : P
Is that computer currently stable? I ran an Amptron (equal to PCChips)
socket 7 board in early '98 and had more trouble with that damn thing than
it was worth!

I've never had a problem with mine.

As for a new CPU for your PC I'd look for a K62+ 500 or K6III+ 450 first
or perhaps a K6III at 400 or 450Mhz, failing that I'd go with a K62 500.

The 'plus' series are mobile chips and are fairly rare, but they are
excellent overclockers thanks to their being manufactured on an .18 micron
process rather than the .25 micron process of non-plus K62's and K6III's.
They also run cooler because of their .18 micron design which may be more
beneficial to you as you likely can't go faster than about 500Mhz with
your motherboard anyway. They also have the same extended 3DNow!
instruction set that the Athlon's do and most importantly they have full
speed, on-die L2 cache (128K for the K62+ and 256K for the K6III+).

I checked the specs on the plus-series; their core voltage is 2.0V. My
board only goes down to 2.2V. You say they are good
overclockers--could they tolerate the 2.2V? Or should I cross them off
the list and stick with the non-plus series?

The regular K6III's are also somewhat rare and probably expensive to buy
now. They have 256K of L2 cache also which really helps their performance,
but are difficult to overclock. Obviously that's not a problem if you plan
on running stock speed though.

Going rate on eBay seems to be $45-$50 for the K6III-450+, about $5
less for the non-plus version. I can't even find a listing for a
K6-2+.

As for the K62 500, it is probably the easiest to find and probably will
be the least expensive also. In fact www.newegg.com has them for $17
shipped right now. However, it has no advantage over your current CPU
other than clock speed.

Any of the above processors will run at speeds below what they were
designed for, they also will all run on all of the available bus speeds
you have. If you try a certain bus speed and find it's not stable then
your problem likely lies elsewhere in the system.

Checked on your link to newegg.com. K6-2/500 listed at 100MHz FSB,
multiplier 5 to get to 500MHz. Does that imply that's the only way to
get to 500 or can I try 83*6 instead (with any possibility of
success)? I see the K6-III/400 could reach 400 by either 66*6 or
100*4. The K6III 400 might be tempting versus the K62 500 if the
increased cache makes up for the 100MHz difference in processor speed.

Thanks again.
RobertC

 

[philo]

"philo" <[email protected]> wrote in message

Checked out SpeedFan; thanks for the tip. I'll definitely use it.


A memory upgrade is definitely planned regardless of the CPU upgrade.
I've been trolling eBay for the last couple days looking for an
additional 64MB... people keep overbidding me at the last moment... if
I find a good Buy It Now offer I'll likely snap it up.

The only trouble with ebay is that half the time I can find *new* stuff
for less money...but if you keep at it...you should eventually get what you
are looking for.

My "standby" machine is an AMD-450 with 128 megs of ram
and it works quite well actually

 

[Nate]

I've never had a problem with mine.

Excellent, I may have simply had a bum board.

I checked the specs on the plus-series; their core voltage is 2.0V. My
board only goes down to 2.2V. You say they are good overclockers--could
they tolerate the 2.2V? Or should I cross them off the list and stick
with the non-plus series?

Yes, they are designed to run on 2.0 volts, but they will work on 2.2 if
that's as low as your board will go. Some motherboards have undocumented
core voltage settings, but that would require some googling and/or
experimenting on your own to see if your board does. Worst case if you run
a plus chip at 2.2 volts is it runs a bit warmer and still outlives it's
usefulness.

Going rate on eBay seems to be $45-$50 for the K6III-450+, about $5 less
for the non-plus version. I can't even find a listing for a K6-2+.

I guess it depends on how much you are willing to spend... $45-$50 is more
than I would put into a socket7 processor personally, not that I think
socket7 is useless, it's not at all. Just that it wouldn't be worth $50
for a CPU to me.

Checked on your link to newegg.com. K6-2/500 listed at 100MHz FSB,
multiplier 5 to get to 500MHz. Does that imply that's the only way to
get to 500 or can I try 83*6 instead (with any possibility of success)?
I see the K6-III/400 could reach 400 by either 66*6 or 100*4. The K6III
400 might be tempting versus the K62 500 if the increased cache makes up
for the 100MHz difference in processor speed.

The K62 500 will run at 500Mhz or below no matter how you get it there, so
I would try 83x6 and see where that got me. If the 83Mhz FSB didn't work,
then you could easily drop down to 75x6 and run at 450Mhz.

Also as was mentioned in another post, you may have some trouble getting a
plus series chip to run on certain motherboards. If your boards BIOS
doesn't support the plus chips, you may have to set the CPU to run at
300Mhz and use some Windows based utilities to boost the speed back up.
That may be more trouble than it's worth, and won't do you any good if you
don't use Windows. Thanks to Biff for reminding me of that.

You will likely want to stay with non-plus K62's and K6III's for something
that should be able to run fine after setting the jumpers, without worrying
about BIOS compatibility etc. If you find a deal on a K6III (or don't mind
the prices you've found already) then that's the way I'd go. When I was
using K6's for my main computers I found that a K6III at 400Mhz 'felt' as
fast as a K62 at 500Mhz. Depending on your application one CPU may be more
appropriate than the other, but both will be faster then the 300 you've
got now.

Also, if you want a little speed boost right now, why not run your K6 at
75x4? It's still 300Mhz, but you should notice a bit more performance due
to the increased I/O. Hell try it at 83x3.5 if you want to see if your
machine will run an 83Mhz FSB, worst thing that can happen is it won't
work and you have to change some jumpers.

Thanks again.
RobertC

Glad to help, sorry it took so long to reply...

Good luck,
Nate