I don't see why it wouldn't work!

Personally I would just stick with an IntelDX4 overdrive. They have plenty of grunt and you don't need to mod anything 😀

^ really? didn't own any of these overdrives ever... are they expensive?
reason why I want to 3.3v mod it is because I already have an AMD486/100 cpu and I won't have to buy anything 🤣

I'd say $20-30?

They are easily recognisable because they come on a little PCB (mini board) with a voltage regulator and a nice black cooler. The IntelDX4 is faster clock for clock than the 5x86 so it's a nice little chip 😀

When I compared the two chips on my Biostar board the difference wasn't major. Certainly not reason to mod a board. The Intel chip universally has better support / easier to get going.

this is the one right? http://www.ebay.co.uk/itm/Vintage-CPU-Intel-O … =item53f99fe610

not to keen on spending ~35e for one 🤣 ... just did a quick global search... I'll put an AmiBay ad but eventually I think I'll just have to mod the mobo 😉

I think I have a spare DX4-100 overdrive I could sell on amibay.

I use a Kingston Turbochip in my 486 which is actually an AMD 5x86-133MHz soldered onto a small PCB with a voltage regulator on it, so it works on 5V only boards (You may still need a BIOS update to support the CPU though).

You could try soldering in a 5V regulator and the jumper headers yourself and see what happens... there may be other components you need to add to make it work - I see TC24 in your photo of the empty regulator solder pads, that looks like it takes a tantalum capacitor.

You could also try a standard AMD 486DX4-100 as I believe a few of those are 5V tolerant. I was running one at 5V for a while and never had problems.

Hmm yea prices aren't THAT cheap. I thought they go for less 😊

yeah I noticed the empty capacitor places, most likely filters... there are another 2 empty cap holders under the cpu socket, all for small tantalum caps... most likely the same value as every other tantalum on the board, they are all marked 106F (10 uF?)

From what i can tell comparing an chaintech SLD/SLP with a four pin Voltage regulator..
I didnt do any modification by me self.. I tried only once on an UMC chipset one.. From what i can tell.. Some VRM modifications are harder then other ones..

1. You need to desolder that three-pin dupont bridge.. Instead of that you need to solder an 3 leg VRM in.. Which one you can take i really dont know, maybe there are some differencens talking about different brands..
2. You need to solder that Tantalum-capicator in..I red 106F on mine (thats soldered in that near spot on TC24) Watch out for the polarity..
3. Need to desolder the wire on JP24 (above the first VLB socket) Here you need to solder an single row golden three pins header in.. JP24 is used to select to 3.3volts, and or 4 volts for cyrix processors.

I have checked my other chaintech SLD motherboard i have.. On the same spot, there is also the same tantalum-capicitor with the same value 106F.. ( i only know which value it is, because iam not een specialist about electronics, but learn about those try-outs..

^ I suppose you left 3 blank on purpose , since we don't really know... I would assume I need to make JP24 a proper jumper and maybe add the rest of the missing 106F filtering caps... but that might not be necessary

I actually had 2nd thoughts on this... there is no guarantee the BIOS will recognise the amd486/100 cpu and tbh I did some testing with the existing 486/66. The board is great and stable (WAY better that the AmiBIOS mobos I have here with the same hardware and software setup) but I don't know, I think I prefer to make a ss7 build with a low p1/75mhz than a 486 one... still undecided on this
(did some DOOM timedemo benchmarks with the 3 VLB vgas I have: 5424 , 5428 and a WDC 90C33 , they are all behaving the same at ~27fps)

edit: heh, you added #3 with the JP24 info 😊
any idea if the 106F tantalums are indeed 10uF ? 😕

No i was editing my post. Yes JP24 needs to have an header instead of that hardwire.(an three pins one) So it would be possible to set it to 3.3 volts and 4 volts for cyrix processor. JP1, JP2, JPx is only needed to go from 5volt (the three headers closed) or all of the three `open` to get 3.3volt instead.. Maybe the 106F capacitor could be for filtering, but i should also solderd in on the motherboard, so you dont get problems after the modification.. Price of those tantalum-capacitors are very cheap on ebay..

About your second question: Most boards without VRM would do DX4- 100mhz also. If you are lucky it should take an 120Mhz as well.. Why does VRMs are missing is because it was an OEM motherboard.. They did that because customers had an very hard time to upgrade those systems with faster processors.. So the manufacturers wanted that customers buying newer complete computers instead easilly bypassing the restrictions of the motherboards.. So the most boards you find on ebay where from OEMS.. Most retail boards are already gone..

Mau1wurf1977 wrote:

I don't see why it wouldn't work!

Personally I would just stick with an IntelDX4 overdrive. They have plenty of grunt and you don't need to mod anything 😀

Only the overdrive isnt very easy to get for a very low price.. These processor you have to pay for if you want one..
And then, what happens if it dies? An easier replacement wouldnt very easy to find.. If he is doing the mod right he`s have very more options on processors, and speeds.. and an 100Mhz ones arent very difficult to find.. And the prices are low (for recent gold prices)

keropi wrote:

I actually had 2nd thoughts on this... there is no guarantee the BIOS will recognise the amd486/100 cpu and tbh I did some testing with the existing 486/66.

On my PCI 486 3dbench improves from 52 to 66 when going changing the multiplier from 2x to 3x on an IntelDX4. Yes it's faster, but it's not going to make laggy games smooth 😀

The 486DX2 66 MHz is THE 486. The IntelDX4 and 5x86 are nice chips, but I like your thinking: Super Socket 7 🤣

did a BIOS dump and saw these cpu names inside:

180386DX  80386SX  RapidCAD  80486DX  80486SX  80487SX  80486SX2  80486DX2  Cx486SLC 
2Cx486DLC  Unknown  P24T  Cx486S  Cx486S2  PENTIUM  Cx486DX  Cx486DX2  Cx486SLC2 
3DX4  TI486SXL  TI486SXL2  U5  Am486  P54C  TI486SXLC TI486SXLC2 	Am486DXL2  P24D

does the "DX4" apply to AMD's 100mhz cpu?

keropi wrote:

did a BIOS dump and saw these cpu names inside:

does the "DX4" apply to AMD's 100mhz cpu?

Seeing there is only one DX4 entry my bet is on it being for Intel 😒

EDIT:

Why not put the chip in, drop a heatsink at the top and quickly POST it?

as-is it detects the AMD A80486DX4-100NV8T as an "486 DX2 100mhz" ... had a look on the mobo silkscreen and BC8 that should be OPEN for 3x multiplier has a resistor sodlered ... I give up the whole 3.3v project, it seems they went to extra trouble to really remove the option :\

Maybe i can help you out with a newer bios.. I guess i have one from 95 i thought.(only its from an SLD/SLP motherboard, but chipset seems te be the same) Mine only has problems with the AMD 5x86 p75-133 Mhz processor. AMD DX4-100Mhz,and 120Mhz seems to work well. Only the bios have the 2094 year bug.. I only recommend you the use another CMOS 27C512 chip.

I only dont know which voltage rating the VRM must have, i guess that would need a 5V one.. (iam think it using the existing 5volt line to convert it to lower voltages.)

Iam out why you need that capacitor. Its for stability.. If i where you i should go further on this..

why not, once I discover what the missing regulator is I'll just add it along with the cap, it is indeed needed 😀
also getting a new eprom programmer, a "True usb gq-3x" one from a fellow on amibay, so I can play again with eproms 😀

I think, where are in the same boat now.. I can help with the things i know. I like to know more about those Voltage regulators.. and i also have some boards thats missing that vrm thing. I want to try to learn more so getting to know what iam doing to solder the vrm parts back to those motherboards, so i could be happy to also using 3.3 volt processors, instead only 5volts.