A7S8X-MX and FSB

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ernest

I have an Asus A7S8X-MX and XP1800. I want to run at lower speed to
make it cooler but for some reason when I set FSB to 100MHz instead of
133MHz, the system refuse to boot (no beep/screen/bios, nothing). Any
thing I need to do to get it underclocked?

Ernest
 
to run motherboards at SLOWER than their rated speed usually you have to
switch a jumber on the motherboard, check the manual on how to slow the
motherboard down. I know on my Asus A7N8X theres a jumper to do it with. The
default is 133mhz to 200mhz <thats 266mhz to 400mhz> switch the jumber and
bang, you're down to 100mhz <200mhz actual> Good luck.
BTW, why not just buy a better heatsink/fan? Or, clean the dust bunnies out
of the heatsink? I clean all heatsinks and fans in all of my systems about
every other month.... it builds up!! Believe me. Especially if they sit on
the floor.



--
{SFU} Jackyl

MSI K7N2 Delta ILSR
Athlon XP2500
ATI Radeon 9800 pro
1gb Geil DDR 3200 DC
 
to run motherboards at SLOWER than their rated speed usually you have to
switch a jumber on the motherboard, check the manual on how to slow the
motherboard down. I know on my Asus A7N8X theres a jumper to do it with. The
default is 133mhz to 200mhz <thats 266mhz to 400mhz> switch the jumber and
bang, you're down to 100mhz <200mhz actual> Good luck.
Click to expand...

No, it's not 266-400Mhz, it's 266Mbps to 400Mbps, and 100 Mhz isn't
actually 200MHz, it's actually 100Mhz.:-) See The Real Front Side Bus in
link below.
 
Wes Newell said:
No, it's not 266-400Mhz, it's 266Mbps to 400Mbps, and 100 Mhz isn't
actually 200MHz, it's actually 100Mhz.:-) See The Real Front Side Bus in
link below.
Click to expand...
I agree, the FSB clock rates, are half the rates normally quoted, but the
bus transfers 8 bytes at a time, not one, so at 100MHz, 2 transactions per
cycle, transfers potentially 1600MBps. Your figures are just as 'wrong',
but for a different reason. Also 'b' is the symbol normally used for bits,
not bytes, so using this terminology, the same 100Mhz bus could actually
transfer 12800Mbps.

Best Wishes
 
Yeah I switched the jumpers that's why I said I put it to 100MHz. It
locks up after that. I cannot change much of the HSF because of space
limitation. I've got pretty much a good HSF... I can't even use a
CNPS7000 or Volcano7+...

Ernest
 
I agree, the FSB clock rates, are half the rates normally quoted, but the
bus transfers 8 bytes at a time, not one, so at 100MHz, 2 transactions per
cycle, transfers potentially 1600MBps. Your figures are just as 'wrong',
but for a different reason. Also 'b' is the symbol normally used for bits,
not bytes, so using this terminology, the same 100Mhz bus could actually
transfer 12800Mbps.
Click to expand...
Their repesentation was for a single line, not the whole bus. I simply put
the right nomenclature behind it, and it is correct for 1 line of the bus.
Nowhere in my response did I represent it as the bandwidth, which includes
all lines of the bus. Had I wanted to represent the bandwidth I would have
used MBps or GBps and not Mbps (megabits per second).
 
ernest said:
I have an Asus A7S8X-MX and XP1800. I want to run at lower speed to
make it cooler but for some reason when I set FSB to 100MHz instead of
133MHz, the system refuse to boot (no beep/screen/bios, nothing). Any
thing I need to do to get it underclocked?

Ernest
Click to expand...

I noticed in Google, there was mention of the documentation of the
FSB jumpers being wrong. Maybe it is wrong in the printed manual,
and corrected in the downloadable manual ? Download this and have
a look at PDF page 30:

http://dlsvr03.asus.com/pub/ASUS/mb/socka/sis741GX/e1766_a7s8x-mx.pdf

This is the coding as recorded in the Barton datasheet, for the
CPU clock speed the processor wants. Compare this info to the jumper
info in the manual.

FSB_Sense[1] FSB_Sense[0] Bus Frequency
1 0 RESERVED (and likely to be 100MHz)
1 1 133 MHz
0 1 166 MHz
0 0 200 MHz

It could be that you have selected a clock speed which is too high
for that processor. Hope it isn't fried...

Paul
 
This is the coding as recorded in the Barton datasheet, for the
CPU clock speed the processor wants. Compare this info to the jumper
info in the manual.

FSB_Sense[1] FSB_Sense[0] Bus Frequency
1 0 RESERVED (and likely to be 100MHz)
1 1 133 MHz
0 1 166 MHz
0 0 200 MHz

It could be that you have selected a clock speed which is too high
for that processor. Hope it isn't fried...
Click to expand...

I thought mine is correct and like that but I'll double checked. It
didnt' fried for sure as I've put back to original position and booted.

Do I need to change the FSB/RAM speed ratio and what the heck does SPD
means?

One thing I suspect is that because I can't even see anything (video
card not working), is there anything to do with AGP/FSB frequency? I
remember in the old days there is a BIOS setting to set the AGP and FSB
bus frequency ratio for people to hack around O/C. I don't see it on
the BIOS here. Now it becomes automatic?

Ernest
 
This is the coding as recorded in the Barton datasheet, for the
CPU clock speed the processor wants. Compare this info to the jumper
info in the manual.

FSB_Sense[1] FSB_Sense[0] Bus Frequency
1 0 RESERVED (and likely to be 100MHz)
1 1 133 MHz
0 1 166 MHz
0 0 200 MHz

It could be that you have selected a clock speed which is too high
for that processor. Hope it isn't fried...
Click to expand...

I thought mine is correct and like that but I'll double checked. It
didnt' fried for sure as I've put back to original position and booted.

Do I need to change the FSB/RAM speed ratio and what the heck does SPD
means?

One thing I suspect is that because I can't even see anything (video
card not working), is there anything to do with AGP/FSB frequency? I
remember in the old days there is a BIOS setting to set the AGP and FSB
bus frequency ratio for people to hack around O/C. I don't see it on
the BIOS here. Now it becomes automatic?

Ernest[/QUOTE]

Clock generator chips and the chipsets themselves, are a lot
more flexible than they used to be. The AGP clock on more and
more designs is "locked" to 66MHz (or locked to one of several
preferred settings offered in the BIOS). And, especially with the
100, 133, 166 settings offered with the jumpers on your board,
I would not expect the AGP to stray from 66MHz.

The RAM speed setting can be left at "Auto", if you are
uncertain as to how it should be set. The manual claims
you are offered 5:4 and 1:1 ratios, which would give...

CPU_clock =FSB mem=1:1 mem=5:4
100 FSB200 DDR200 (PC1600) (would be too slow)
133 FSB266 DDR266 (PC2100) ~DDR200 (PC1600)
166 FSB333 DDR333 (PC2700) DDR266 (PC2100)

With the RAM available today, the 5:4 divider is only
needed if you bought PC2100 RAM, and are running the processor
at FSB333. Since I haven't seen a posting about the use of
PC1600 RAM for a long time, I doubt that would be an issue.

As for the memory, you can use memory which is faster than
the numbers above. Memory is backward compatible, so a
PC3200 stick can be used at DDR400 (its rated speed) or
at the slower rates of DDR333, DDR266, or DDR200. The numbers
above are minimum DRAM module speeds. For example, a PC2700
stick could be used for any of the five entries in the memspeed
columns above.

"I thought mine is correct" - I am not saying you made a
mistake. I'm saying that the information printed in the
paper manual that accompanies your motherboard is
incorrect. Asus did not document the jumper settings
properly for your board. In good faith, you selected
the value for 166Mhz, as shown in the manual, but you
might well have got a different frequency by doing that.
The downloadable manual may show different information than
the printed manual, and that is why I gave a URL for that
download, so you could compare the PDF version of the
manual, to the manual that came with the motherboard.

Asus also got the FSB settings on both A7V400 motherboards
wrong as well, so this is nothing new.

HTH,
Paul
 
How odd that is...., hmmmm, I've been building pc's for over 10 years now,
and as computer bus speeds have went from a whopping 10mhz to my current
board, at 400mhz FSB, I guess I have always missread all the data,
information, manuals, and technical information.... I could have sworn that
FSB speeds were measured in mhz, not mbps. And it was the frequency of the
current, not the data bit transfer rate. <sigh> I guess it's back to the
drawing board for me..... well, anyways.... I guess different people measure
things in different ways.
I myself always use tech sheets and manuals though.


--
{SFU} Jackyl

MSI K7N2 Delta ILSR
Athlon XP2500 @400mbps <I guess........>
ATI Radeon 9800 pro
1gb Geil DDR 3200 DC
 
How odd that is...., hmmmm, I've been building pc's for over 10 years now,
and as computer bus speeds have went from a whopping 10mhz to my current
board, at 400mhz FSB, I guess I have always missread all the data,
information, manuals, and technical information.... I could have sworn that
FSB speeds were measured in mhz, not mbps. And it was the frequency of the
current, not the data bit transfer rate.
Click to expand...

You are correct that bus speeds or measured by the clock frequency in MHz,
but I guess what you don't realize that with the intro of Intels P4, and
AMD's Athlon, the data rate was no longer 1:1 on the bus. So while you may
think that the the FSB of your current system is 400MHz, it isn't. To get
the real speed of the FSB with a P4, simply divide the advertised BS
marketing speed by 4 to get the real clockspeed of the bus. With AMD
Athlons, divide by 2. Now, how they came up with the inflated MHz numbers
is real simply. In Intels case, they just looked at the data rates being
4:1 with the P4, so they just changed the data rate of 400Mbps per line,
to 400MHz. Total BS, but that what thye did. AMD originally didn't do
this, but used the term 200FSB, 266FSB, etc without the MHz symbol, but
starting sometime even they went to the bogus numbers in their
advertising. Their data sheets did however still have the correct speed
measured in clockspeed by MHz. Some claim this to be the effective
clockspeed, but that's just more smoke to keep the numbers higher for
marketing hype.
<sigh> I guess it's back to the
drawing board for me..... well, anyways.... I guess different people
measure things in different ways.
I myself always use tech sheets and manuals though.


MSI K7N2 Delta ILSR
Athlon XP2500 @400mbps <I guess........> ATI Radeon 9800 pro 1gb Geil
DDR 3200 DC
Click to expand...
Download the data sheets for the Model 10 Athlon XP if you want the real
speed. The defaulkt FSB clockspeed of the 2500+ is 166MHz And the default
for the 3200+ is 200MHz, not 400MHz. To AMD's credit, thier data sheets
are still correct showing the proper speed. The one Intel data shit, er
sheet, I looked at wasn't, showing the BS 4x clockspeed.

There's another explanation of this under The Real Front Side Bus in the
link below.
 
Paul,

Thanks for all your help and you know what, we're both right: my
printed manual is exactly the same as the online one, and the online
one is STILL WRONG!!! I just put the jumpers on the supposedly 166MHz
setting and BAM I got 100MHz. Unbelievable.

I also fixed up a few thing including a case fan with air duct to HSF.
Now I can get it down to about 58C, however, not without underclock it
to 100MHz FSB (1150MHz). On the other hand, the copper HSF is still
not steaming hot... doubled checked the position and seems ok. Overall
I can live with 1150MHz so I feel better running it 24/7 @ 58C.

Thanks everyone again for helping!!

Cheers,
Ernest
 
ernest said:
Paul,

Thanks for all your help and you know what, we're both right: my
printed manual is exactly the same as the online one, and the online
one is STILL WRONG!!! I just put the jumpers on the supposedly 166MHz
setting and BAM I got 100MHz. Unbelievable.

I also fixed up a few thing including a case fan with air duct to HSF.
Now I can get it down to about 58C, however, not without underclock it
to 100MHz FSB (1150MHz). On the other hand, the copper HSF is still
not steaming hot... doubled checked the position and seems ok. Overall
I can live with 1150MHz so I feel better running it 24/7 @ 58C.

Thanks everyone again for helping!!

Cheers,
Ernest
Click to expand...

Thanks for posting back with your results. I had assumed the PDF is
correct, and now I know both printed and PDF are wrong!

Paul
 
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