It's probably just a slow chipset/motherboard. Do you have cache? That might be a factor. The 25 Mhz FSB doesn't matter when concerning ISA only systems. Also check that the machine is ACTUALLY running it at 75 Mhz, and that it's not at a value below that.

Well i do have cache but it aint big ( 64kb ) as can been seen on http://th99.classic-computing.de/src/m/S-T/31924.htm, i dont know that much about cache and how much is recommended.

tabm0de wrote:

Well i do have cache but it aint big ( 64kb ) as can been seen on http://th99.classic-computing.de/src/m/S-T/31924.htm, i dont know that much about cache and how much is recommended.

When looking at your pictures it looks like your cache sockets are empty.

Filling your sockets with 8x32KB = 256KB cache is not very expensive and well worth it. 😀

True, i didnt really think about that, for some reason i had it in my head i did have 64kb but as you said i dont 😉

Dx4 overdrive only supports 3x multi, so unless the bus is not 25mhz, it must be running at 75mhz internally. Check bios to make sure internal cache is enabled.

Here is ss from cachechk

That looks okey.

The systems performance would improve if you get some L2 cache.

You probably need nine 32K x 8 15n DIP28 SRAM chips, 20n chips would probably be fast enough but I don't think they are any cheaper.

Member feipoa can probably tell you where it's best to source these chips but I think the cost will be about $20-$30 with shipping for 10 chips (1 spare in case there is a bad chip in the lot).

Another option is to buy a tested motherboard with the needed cache chips (~€40 with shipping from Russia or the Ukraine), move the chips and then sell the now cacheless motherboard on Tradera for €20 - €30. The risk is that the package can get stuck in customs until you pay the "protection money" but I have bought at least 10 motherboards from Russia and the Ukraine and every single one have slipped through the net.

So I dont know but this could be the problem???

The built in cpu is 25mhz and the system bus is at 10mhz? and can be changed to 8.33mhz only?

Those bus speed numbers look like ISA, not FSB. 10MHz is actually an overclock for the ISA bus. If your FSB was running at 10MHz, the SX would have been, also - it has a 1x multiplier.

tabm0de wrote:

So I dont know but this could be the problem???

The built in cpu is 25mhz and the system bus is at 10mhz? and can be changed to 8.33mhz only?

Cachechk shows that your CPU is running at the speed it should run.

That diagnostic program from 1992 dosn't know that your CPU runs at 3x FSB so it only shows the ISA bus at 10 MHz like member jade_angel already mentioned and the "CPU" (1x FSB) at 25 MHz but in reality it runs at 3x FSB = 75 MHz.

The ISA bus speed is not the same as the FSB but the number the diagnostic programs calls "CPU" is the FSB bus speed.

Im waiting for a dx2 50 overdrive, i read it could be that the port only support 5v? and not 3.3?

tabm0de wrote:

Im waiting for a dx2 50 overdrive, i read it could be that the port only support 5v? and not 3.3?

Voltage do not affect performance but normal non Overdrive Intel DX4 CPUs can not handle 5V as they are made for 3.3V. All Intel 486 DX4 Overdrive CPUs (like the one you already have) are made for 5V even if the CPU core it self uses 3.3V. That's what the extra components soldered on top of the CPU are for, they take the 5V the motherboard supplies and drops it down to the 3.3V the DX4-75 CPU core needs.

This thread would benefit from a merge with your thread about this system in the System Specs forum as half of the discussion and all your pictures showing us the system is in that thread.

On the other hand I never understood why DX2 overdrive ever existed ... It's not like the regular DX2 wasn't already compatible with every mobo with a socket ... (Except for the DX2 overdrive that goes in the 487 socket)
I've got one of those and there is no difference to my knowledge