System dies when restoring default settings

[DrMrLordX]

My old Sempron system got a little flaky early yesterday (apparently some of the profile setting files for my wife's XP login were corrupted) so I took the old Sempron 2800+ down from its relaxed OC of 1920 mhz to default in the BIOS, and the system them refused to POST. It still powers on but there are no telltale BIOS beeps. Just some spinning fans and nothing else. I'm not 100% sure where the CMOS clearing jumper (JP1) is on my old vnf3-250 but there are only three jumpers on the board that have the same dimensions, and two of them are labeled differently so I think I found it by process of elimination, not that messing with it did me any good.

All I did was drop HTT back down from 240 to 200, reset the HT multiplier from 4x to 5x, and put the RAM back on default timings instead of the minor RAM underclock I had.

The net effect was that the processor and HTT speeds were lower but the HT speed went up by 40 mhz and the memory was running about 7 mhz faster. And that, by some bizarre process, has rendered the machine inoperable.

My guess is the board died. Swapping the two DIMMs did nothing, nor did booting the machine with only one DIMM (tried this with both sticks). The likelihood that both sticks went bad and that they became so sensitive that they would not/could not function at their default speed is very, very low. The fans are still spinning up so it probably isn't the PSU, even if it is a well-worn Antec Smartpower 400W (one of the old ones that only puts out 18a on the 12v rail). Sadly, I have no means by which to test the motherboard, CPU, or RAM individually.

Any other thoughts here? I really don't see it being the CPU since it probably wouldn't die when being restored to default settings. I'd rather it was the CPU though since it would be the easiest component to replace. I really hope it isn't the RAM since DDR prices are high and the DIMMs I have are both single-sided making them quite useful for some s754 owners.

 

[DrMrLordX]

So, any thoughts? It still seems like the mobo to me but I could be wrong. Don't see why the CPU or RAM would die/fail to post given the circumstanc.es

 

[ionoxx]

The clear cmos jumper is usually within 2cm of the battery. Or just pull the power cord and remove the battery for 10 minutes.

I'd say its more of a bios issue for the failed post. As for the rest... run memtest and a hard drive test. Usually hard drive manufacturers offer a diagnostic tool on their support websites. You can find them on the Ultimate boot CD that you can download somewhere (from another PC... I'm sssuming you have another PC since you're posting here )

 

[DrMrLordX]

The harddrive is fine. I plugged it into my X2 box upstairs and backed up all the data (then wiped it 'cuz it needed it anyway).

Problem is that I do not have any s754 hardware present to test the motherboard, CPU, or RAM. I don't even have an AGP system to test the vid card.

I found what is likely the clear CMOS jumper but clearing it did not help . . . I may have to scan the board just to make sure, but it was not located next to the battery. And yeah, I guess I can just pull the battery.

 

[Zap]

Originally posted by: DrMrLordX
reset the HT multiplier from 4x to 5x

That was your mistake. 4x is the default HT multiplier for socket 754. 5x is for socket 939. Perhaps it didn't clear in CMOS? Double check the location of the clear CMOS jumper, failing that remove the CMOS battery for a time as ionoxx suggested.

 

[ionoxx]

nice catch zap, 4x on the Socket 754... i forgot about that!!!!

 

[DrMrLordX]

Okay, you were right Zap, as was ionoxx for thinking of the battery. Pulling the battery did the trick, and it turns out the only thing preventing my system from POSTing was the 1000 mhz HT speed. The board is only programmed to roll back HTT when it's on an unstable OC, but it could not do anything but retreat to 200 mhz HTT, so it was stuck.

So it was the board, but not for the reasons that I thought.

Thanks for the input, and boy do I feel silly for not remembering my board's upper HT limit (and for not thinking to pull the battery).

 

[Zap]

Originally posted by: DrMrLordX
Thanks for the input, and boy do I feel silly for not remembering my board's upper HT limit (and for not thinking to pull the battery).

:thumbsup: Glad you got it sorted out, and yeah, we all make silly mistakes. Did I tell anyone here about the time that I didn't plug in the secondary PSU in a system (one of those drive bay GPU boosters) and the system wouldn't POST? Or the time I hooked up the power swich wrong, and the system wouldn't boot?

 

[nerp]

Wow. Blast from the past. I'd never have remembered the 754's 4x HTT. Time flies when you're having fun. Glad things are back to normal.