Your motherboard might be an earlier revision (hence no VLB slots and no Socket with a latch).

All the CPU's you mentioned are 3.3V CPU's and the problem is that your motherboard only supports 5V CPU's.
The fastest CPU that will run on this motherboard (excluding any "Overdrive" CPU's) is your 486DX2 66 MHz (I think that there were 3.3V versions as well so, just check before you install a faster CPU).
If you want more speed, then another option is to try and acquire one of the 486 "Overdrive" CPU's (or even a Pentium Overdrive - P24T). The Kingston Turbochip (a rebadged AMD 5x86) also came with a VRM that allowed you to install that CPU in earlier 486 motherboards that only supported 5V CPU's. However, some of these CPU's are quite rare these days and, if you do find one, expect to pay a premium.

As I understand, this motherboard can be modded to also accept 3.3V CPU's: ASUS VL/I-486SV2 to GX4 conversion + Am5x86 support on Rev 1.7
This is, of course, at your own risk and might also not be possible, depending on what motherboard revision you have.

jesolo wrote:

Your motherboard might be an earlier revision (hence no VLB slots and no Socket with a latch). […]
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Your motherboard might be an earlier revision (hence no VLB slots and no Socket with a latch).

All the CPU's you mentioned are 3.3V CPU's and the problem is that your motherboard only supports 5V CPU's.
The fastest CPU that will run on this motherboard (excluding any "Overdrive" CPU's) is your 486DX2 66 MHz (I think that there were 3.3V versions as well so, just check before you install a faster CPU).
If you want more speed, then another option is to try and acquire one of the 486 "Overdrive" CPU's (or even a Pentium Overdrive - P24T). The Kingston Turbochip (a rebadged AMD 5x86) also came with a VRM that allowed you to install that CPU in earlier 486 motherboards that only supported 5V CPU's. However, some of these CPU's are quite rare these days and, if you do find one, expect to pay a premium.

As I understand, this motherboard can be modded to also accept 3.3V CPU's: ASUS VL/I-486SV2 to GX4 conversion + Am5x86 support on Rev 1.7
This is, of course, at your own risk and might also not be possible, depending on what motherboard revision you have.

Thanks for the reply. Turns out after looking closer, the board is the ISA-486SV2 Version 3.1, very similar to the board I posted but where the VLB slots should be, there is only the solder points. And the heatsink of course is the non-latch socket.

I just dropped in the AMD DX4 120 and it booted! Woot 😁 Jumpers are set to Intel-AMD/DX-DX2/40MHz-fsb

Unfortunately, the post screen, nor the bios is showing me the CPU Type or Speed, so I'd need further testing to see what it's actually posting as, hopefully the 120Mhz. I'm temped to drop in the 5x86 133 AMD, however since the Board is only ISA, I don't see a point even if it does work. One thing to mention, the DX4 120 run's hot, and the heatsink is shallow and clips on.

dave343 wrote:

Unfortunately, the post screen, nor the bios is showing me the CPU Type or Speed

On these older systems, there was no reliable way for the BIOS to determine the CPU (the Pentium was the first to introduce the CPUID instruction that can return a string describing the CPU brand and model).
So the BIOS can only do a basic check for some CPUs that it knows how to detect. You are using CPUs that are probably too new for the BIOS to detect.
Doesn't mean they don't work properly, but you'll have to use some benchmark/system info software to get more accurate detection.

Yeah... I just noticed after the "Wait...." it does end of going to the screen where it displays a cpu type... It's reporting it as a 486 DX Class CPU @66mhz. This is with the fab set to 40mhz. When I change the fsb to 33, I still get 66mhz posted. Now there are two additional jumpers that mention cpu-clk, one is ND/1D and the other jumper setting is for TD26/2D ? I'll have to look those up.

Does your motherboard have voltage settings?

Some of the bare bones or earlier boards will have 5V only, your running a 3.3V CPU and will kill it with 5 volts if its hardwired.

dirkmirk wrote:

Does your motherboard have voltage settings?

It doesn't, as was established earlier in this thread. Must be why that DX4-120 is running hot.

dirkmirk wrote:

Does your motherboard have voltage settings?

Some of the bare bones or earlier boards will have 5V only, your running a 3.3V CPU and will kill it with 5 volts if its hardwired.

No, I assumed it was auto adjusting down to 3.3/3.45, but if not then it's running at 5V 😐
Anyways, I can't get it to recognize anything other than 66mhz... unless it's just telling me that, regardless of what the FSB setting is.

I killed a DX4 like that when I was a kid. You can try to put a voltage regulator in there, but that's gonna be some pretty precise work.

Use an Overdrive IMO, or get a 3.3V board.

Jed118 wrote:

I killed a DX4 like that when I was a kid. You can try to put a voltage regulator in there, but that's gonna be some pretty precise work.

Use an Overdrive IMO, or get a 3.3V board.

I've been looking for a PCI based 486 board for a while, just waiting for the right price on eBay.

I wouldn't run a 3.3V CPU on this motherboard. It doesn't support 3.3V CPU's and it's only a matter of time before you kill that CPU.