ASRock K7VT4 and XP2600+ not stable at 333 FSB

[kilabyte]

I have just built a system using a K7VT4-4x AsRock motherboard. It is fitted with a 333fsb AMD XP2600+ CPU and 512mb of DDR 333 2700 memory.
When the jumper on the board is set at 333 the system is really unstable, it keeps looking up or coming up with DLL errors in Windows ME within minutes.
I tried changing the memory for other and it has the same problem.
However when I set the jumper to FSB266Mhz it is totally stable and will run for days without showing any problems (other than it then shows as a XP2000+ and runs slower!).

The CPU temperature is fine at between 37c and 41c at all time (with either FSB setting).

Has anyone got any ideas. Is it worth me putting jumpers on the FIB so I can increase the multiplyer to bring it back up to a 2600+ rather than a 2000+ as it is showing as now?

[Strawbs]

Are you sure your 2600+ is a 333mhz model, there are 3 different 2600's, one is 266mhz, another is 333mhz t'bred and the third is 333mhz barton.

Check out the Bus and Multiplier settings, along with the different ID numbers on This page! (http://www.thedigerati.us/info/amdcpuchart.html). Kepp us informed of your findings.

:t

[kilabyte]

It certainly said 333 on the label on the CPU. I will have to take the fan off and check the full number when it has finished encoding the DVD it is doing at the moment (could be many hours yet!).

What in practical terms is the difference between Barton and T'bred (don't they both work OK at 333)?

[Strawbs]

They are both 333mhz, it's just that the Barton has 512kb L2 cache as opposed to T'bred having only 256kb, The extra L2 cache should help with things like "DVD encoding".

If it is definetly a 333mhz model and you can't set the FSB and multipliers as specified in the chart, I would suspect you have a hardware problem that needs chasing.

:t

edit: there are differences with the actual processor speeds also.

[Strawbs]

There is a BIOS update for your board, it relates to an issue with the 2600+ (although not your particular issue), If you haven't already done so ...you should flash the BIOS anyway.

BIOS Update! (http://www.asrock.com/support/Download/dl_k7VT4-4X.htm#bios) :t

[kilabyte]

I have updated the bios and it has made no difference.
Check the CPU and it is a T'bred 333mhz.

Right this is what I have done and upto now it is stable and working great.

I have kept the FSB at 266 set by jumper rather than auto in bios.
Set the multiplier at 16x by placing jumpers on the FID rather than letting the bios set it on auto at 12.5.
It nows shows as an XP2600+ running at 2.13GHZ.
Sisoft Sandra is giving Dhrystone at 5797 and Whetstone at 2900 with a PR rating of 3118.
And the CPU is actually running cooler at 34c (But it is at night in a cooler room!).

Is it fine to leave it at this setting or is it going to do any harm to the CPU?

[Strawbs]

It won't harm it running at that speed, but your system will not perform to the standard it is supposed to, i.e. with your FSB running at 266mhz instead of 333 you lose system wide performance benefits: file transfer, etc... will be slightly slower than they should be.

The problem may not be with the processor, it could be that your RAM is faulty.

you can download Memtest86 (http://www.memtest86.com/), install it to a floppy disk and boot to the disk to test the Ram for errors, it takes at least an hour to run the test thoroughly, but it may give you some piece of mind.

:t

[RamonGTP]

What memory timings are you using? Its possible that your DIMMs are whats causing the trouble when running at 166fsb.

[kilabyte]

RamonGTP looks like you were on the right lines.

Fingers crossed I have sorted it after talking to one of the IT guys at work.

I had let the motherboard auto select the speed for the ram. The other option was to select 166. He suggested that if at post the motherboard did not pickup on the correct speed for the ram it could then set it incorrectly and you would not know. Diagnostic software would round it up or down to the nearest used regular setting, even if it was say 20% out, which would be enough for the faults.

I have now reset the board to the 333mhz FSB and selected the manual setting for the Ram at 166 and it has been running fine for the last day and night. :D