Hopefully it is just a jumper.

Charleston wrote on 2021-07-24, 20:29:

Issue with this is that (this) dx4 is 33.3x3 not 50x2 to reach 100mhz.

And Yes ! checked your S-spec SK051 and it is locked at 3x Multiplier unlike SK050, SK053 and SK096 plus some other models which can run either 2x or 3x.

Horun wrote on 2021-07-24, 22:36:

Hopefully it is just a jumper.

Charleston wrote on 2021-07-24, 20:29:

Issue with this is that (this) dx4 is 33.3x3 not 50x2 to reach 100mhz.

And Yes ! checked your S-spec SK051 and it is locked at 3x Multiplier unlike SK050, SK053 and SK096 plus some other models which can run either 2x or 3x.

Well, let's hope the PC being forced into sleep mode was the root of all evil, although it's still strange that it booted only when set to the 5v settings. I'm not knowledgeable enough.

Well... sadly removing jp21 did absolutely nothing. Tried every single configuration of clkmul and clock speed. Guess my next step is testing the regulator with an oscope.

I found another similar board here with a high enough quality image to be useful.

https://www.ebay.com/itm/334082936117?hash=it … 6oAAOSwGsRg-0LF

I'm noticing they don't have the second voltage regulator like package on Q4. Right and down an inch or two from the voltage regulator that supplies the 3V for those cpu types.

Does anyone know what the purpose of this package is? I'll have to have a look and find it's datasheet when I get home if not.

Thank you

I'm also noticing now some browning on the solder joints of my regulator for 3V. I'm wondering if that's a sign something went bad or if it was messed with at any point and that's leftover burnt up flux.

Edit: I'm gonna retest the regulator... Probably just gonna check the vcc and vss through the socket instead of trying to hold my probes on the regulator itself. I'm still a bit confused as to what the second package is though, a second regulator? The same thing?

Edit2: I'm thinking I'll replace the regulator with a TIP31C, but I'll confirm what the swap will be once I get to it. I'm noticing other boards of this type (other versions at least) seem to all use a TIP31C so I'll just go with that.

Update: it's working now. Replaced the regulator with a tip 127. Looked at the back of the board more closely since I hadn't taken a look at it since installing it. Whoever last replaced the transistor did an absolutely awful job.