What mainboard are you using?
How do you know it doesn´t wake up from standby when it doesn´t start at all?

does not start from off, computer (PSU) start but because is an AT psu. Mainboard is the original IBM Board coming with this model IBM PC330DX4, it support intel 486cpu, Cyrix 5x86, POD83 but not AMD 5x86. all not ufficially except for the intel cpu provided with the computer: intel 486 DX4.

Those boards didn't support Pentium Overdrive properly without an interposer, so I am thinking it's a year or two too old to support write back also.

Do you know for sure that the CPU is not dead (have you tried it in another board)?

BitWrangler wrote on 2022-06-23, 19:15:

Those boards didn't support Pentium Overdrive properly without an interposer, so I am thinking it's a year or two too old to support write back also.

I guarantee you that POD83 works, I play it quake on this computer. Cpu id tells me that he also has the chache in WB, too. However, his original dx4 tells me that he has the chache wt. I do not understand this mixture ... the incredible thing is that to make the POD work I have to put the boot hard disk on the secondary, otherwise the computer does not boot. Apart from everything, if it were not compatible with the WB cpus, shouldn't the WT start up anyway and get them to work?

debs3759 wrote on 2022-06-23, 19:30:

Do you know for sure that the CPU is not dead (have you tried it in another board)?

I bought it in working condition, but I don't have a second mainboard to try it out

I guess properly means something different to you then 🤣

Bios update maybe?

Some of these chips needed pins pulled high or low to work properly.

Like the setmul pin on some chips, if it wasn’t in a specific state. The chip would not function.

It’s easy to see some of these pins if you examine the socket 1/2/3 tweaker. Link in sig, under pcb projects.

A good place to start is the datasheet for your chip. Google it and give it a read. It will describe the functions of some of these pins and if you need to have them in specific states. You can use a volt meter to check the state your mobo is providing.

Here is an example from a datasheet, (undure if the datasheet applies to your specific chip)

In the case of DX4 it depends on the CPU-revision. Some support write-back L1 some don´t.

As for the POD I´m not sure, maybe it has wb enabled by default. It also brings it´s own VRM and multiplyer setting, because it´s designed to run on mainboards / BIOOSes that originally don´t support it.

The DX2 SX955 supports wb, but when it´s not enabled by the mainboard / BIOS I would assume it runs without wb. I can´t explain why it won´t start at all - except for the case it´s broken.

I've got three SX955 CPUs, all working fine. Doesn't matter which board I plug them onto, they just work. If the board dues not support our is not set for WB the CPU just runs, identified as DX2 and runs in WT mode without any died difference. When WB is enabled (P24D) it's actually a little faster on boards it supports, as expected.

So is you run a regular dx2 just fine, I guess either the SX955 or the board has a little problem.

majestyk wrote on 2022-06-24, 16:19:

In the case of DX4 it depends on the CPU-revision. Some support write-back L1 some don´t.

As for the POD I´m not sure, maybe it has wb enabled by default. It also brings it´s own VRM and multiplyer setting, because it´s designed to run on mainboards / BIOOSes that originally don´t support it.

The DX2 SX955 supports wb, but when it´s not enabled by the mainboard / BIOS I would assume it runs without wb. I can´t explain why it won´t start at all - except for the case it´s broken.

You could try pulling the pin for wb/wt high or low.

They made interposers for this actually, to pull these pins.

i will try some jumper combination as soon as i can, and i will tell the results... tnks for now

I did another test: I came into possession of a DX4 WB, well, with this CPU the computer does not start, exactly as it happens with the DX2 WB. At this point I am thinking of an incompatibility with this memory scheme, in fact the DX4 with which IBM has released this computer and WT (I did not know DX4 WT existed). Strange though because the mainboard is compatible with the POD83 which is WB and the Cyrix 5x86 which seems to me to be WB too. AMD 5x86 on the other hand doesn't work ... maybe for the same reason as DX2 and DX4 ????

The wb pin went to a different spot on some cpus.

Socket 1/2/3 Voltage Interposer Tweaker (Alpha)

Take a look at the socket 1/2/3 tweaker thread ^ and see if any of those mods may apply to your situation.

Sometimes some cpus won’t power on with out a clkmul pin pulled a specific way, or other pins configured correctly.

Also a bios update may be needed.

AlessandroB wrote on 2022-07-07, 20:05:

I did another test: I came into possession of a DX4 WB, well, with this CPU the computer does not start, exactly as it happens with the DX2 WB. At this point I am thinking of an incompatibility with this memory scheme, in fact the DX4 with which IBM has released this computer and WT (I did not know DX4 WT existed). Strange though because the mainboard is compatible with the POD83 which is WB and the Cyrix 5x86 which seems to me to be WB too. AMD 5x86 on the other hand doesn't work ... maybe for the same reason as DX2 and DX4 ????

Are you sure you don't have 2 dead chips?

debs3759 wrote on 2022-07-07, 23:56:

AlessandroB wrote on 2022-07-07, 20:05:

I did another test: I came into possession of a DX4 WB, well, with this CPU the computer does not start, exactly as it happens with the DX2 WB. At this point I am thinking of an incompatibility with this memory scheme, in fact the DX4 with which IBM has released this computer and WT (I did not know DX4 WT existed). Strange though because the mainboard is compatible with the POD83 which is WB and the Cyrix 5x86 which seems to me to be WB too. AMD 5x86 on the other hand doesn't work ... maybe for the same reason as DX2 and DX4 ????

Are you sure you don't have 2 dead chips?

not sure but 2x486dx2 and 1x486dx4... 3 cpu.. all broken... can be but really difficult

Sphere478 wrote on 2022-07-07, 20:17:

The wb pin went to a different spot on some cpus. […]
Show full quote

The wb pin went to a different spot on some cpus.

Socket 1/2/3 Voltage Interposer Tweaker (Alpha)

Take a look at the socket 1/2/3 tweaker thread ^ and see if any of those mods may apply to your situation.

Sometimes some cpus won’t power on with out a clkmul pin pulled a specific way, or other pins configured correctly.

Also a bios update may be needed.

You know were i can find an updated bios (updated... the last one)? i am not a champion in a deep search over the web

AlessandroB wrote on 2022-07-08, 09:23:

Sphere478 wrote on 2022-07-07, 20:17:

The wb pin went to a different spot on some cpus. […]
Show full quote

The wb pin went to a different spot on some cpus.

Socket 1/2/3 Voltage Interposer Tweaker (Alpha)

Take a look at the socket 1/2/3 tweaker thread ^ and see if any of those mods may apply to your situation.

Sometimes some cpus won’t power on with out a clkmul pin pulled a specific way, or other pins configured correctly.

Also a bios update may be needed.

You know were i can find an updated bios (updated... the last one)? i am not a champion in a deep search over the web

Ask here

https://discord.gg/fXXb8NbC

And here

BIOS image collection - requests, discussion etc

And here

DIY Bios Modding guide Jan Steunebrink k6-2+/3+ 128gb

AlessandroB wrote on 2022-07-07, 20:05:

I did another test: I came into possession of a DX4 WB, well, with this CPU the computer does not start, exactly as it happens with the DX2 WB. At this point I am thinking of an incompatibility with this memory scheme, in fact the DX4 with which IBM has released this computer and WT (I did not know DX4 WT existed). Strange though because the mainboard is compatible with the POD83 which is WB and the Cyrix 5x86 which seems to me to be WB too. AMD 5x86 on the other hand doesn't work ... maybe for the same reason as DX2 and DX4 ????

You have a POST card? Any POST codes or completely dead?