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Topic Title: 486-DX overclocking
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Created On: 02/17/2005 12:55 AM
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 02/17/2005 07:56 PM
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eddaweaver
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might work, might not. It depends on whether the motherboard is compatible with the Pentium OverDrive - I believe many m/bs need a bios update first, which harks back to that the original problem is nobody knows what motherboard this is

The CHare site says the POD has got a voltage regulator in it... but randomly changing the jumpers to set the FSB is risky, as that chip is known to sometimes burn up instantly when on a FSB above 33MHz (it has got locked multipliers and some units hate being overclocked).

The 83MHz POD performs roughly like a Pentium 75, so long as there's a reasonable quantity of cache on the motherboard (I should've written L3 cache in the first post, not L2). If a motherboard has got no or little (eg 64kb) of L3 cache, then a POD is not going to be more than a few percent faster than a DX4-100. I doubt an ISA-only motherboard has got much cache on it.

Ironically, you probably need the manual to figure out how much cache is on the motherboard.
 02/17/2005 08:03 PM
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Charlie22911
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i never saw a clock other than 50Mhz, no matter what jumpers i moved where... i found some chips hidden under the built in modem and took some pics of some jumpers:




also it is a packardbell 18cd legend i think...

***EDIT***

there was no bios id string, but there was this:
NJS ID: 99J-123-208

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

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 02/17/2005 08:18 PM
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eddaweaver
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That's a real model alright:
http://groups.google.ca/groups...rd%2...off&sa=N&tab=wg' ">http://groups.google.ca/groups...=&safe=off&sa=N&tab=wg

It looks like others have run 83MHz Pentium OverDrives and DX4OD-100s on this comp, so the motherboard should support 33MHz FSB.

Now, can anyone else dig through Packard Bell's sites and find the motherboard manual and computer model information? I didn't have much luck.

Edit: what is that bad Cmos checksum about, and is the comp using the onboard modem for internet connectivity? It appears to be a 9k modem.
 02/17/2005 08:24 PM
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Charlie22911
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i tried google myself, i edited my post above with this id thing, NJS ID: 99J-123-208 , not sure if it helps though. i found a few hits that sounded like my system but they were inaccurate, like an exposed open PSU for example (mines not exposed or open)


***EDIT***

yeah its a 9K modem thats used, any upgrade recomendations? the checksum is probly when i triped all the jumpers and erased cmos, i unhooked all the drives as well so thats what the other errors are. nothing but power and display are connected.

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

Laptop:
Core i7 2960xm @ 4.2Ghz | 4x4GB Kingston DDR3 1866 | 2x GTX 580m SLI OC 725/1450/1500
 02/17/2005 08:59 PM
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eddaweaver
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for the modem, you should be able to find a second hand 33k ISA modem very cheaply or for free. Be careful to avoid software modems as they'd be hopeless on a 486 (there are ISA winmodems). 56k hardware ISA modems do exist, but they're rare. An external modem is probably going to cost.

See if your motherboard is one of these:
http://j12345.users1.50megs.co...othe...boards.html#486' ">http://j12345.users1.50megs.co.../motherboards.html#486
http://www.uktsupport.co.uk/pb/mb/pbmb1.htm' ">http://www.uktsupport.co.uk/pb/mb/pbmb1.htm

These guys might be able to help you, from that bios string:
http://www.wimsbios.com/' ">http://www.wimsbios.com/

You could try the Packard Bell user forum:
http://forum.packardbell.com/en/' ">http://forum.packardbell.com/en/

It appears Packard Bell only operates in Europe now.

 02/17/2005 09:57 PM
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eddaweaver
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OH, it says "PB450M" in the bios screenshot. That must be the motherboard model.

http://www.uktsupport.co.uk/pb/mb/450.htm' ">http://www.uktsupport.co.uk/pb/mb/450.htm
http://j12345.users1.50megs.co...b450...b450man.asp.htm' ">http://j12345.users1.50megs.co...pb450/pb450man.asp.htm

It says on those pages that 3.3vcore doesn't work on any revision of the PB450 Firehawk despite there being a jumper.

So, for a DX2-50MHz, it'l be jumpered thusly:

J25 1-2
J29 2-3
J31 1-2 & 3-4

and to overclock it to 66MHz, you'd jumper J25 to 2-3.
1-2 gives 25MHz FSB, 2-3 gives 33MHz. If it won't boot after changing that jumper, then you know your DX2-50 won't accept being overclocked.
If it won't tolerate being overclocked, and you still want a faster CPU in there, it looks like the best bet for a faster CPU would be an i486DX4ODPR-100 (DX4-100 OverDrive with vcore converter). You should be able to pick one up for a $ or two, if you can find one. The 66MHz DX2 OverDrive seems to be more common.

Any other faster CPU like the 133MHz AMD is going to burn up at 5v, unless you can find a voltage converter.

It appears to be pointless to try to run a Pentium OverDrive on this motherboard.

http://groups.google.ca/groups...M&hl...G=Google+Search' ">http://groups.google.ca/groups...=en&btnG=Google+Search

You'd better carefully go through the jumpers, as you might've done something like turning off the L3 cache:
http://j12345.users1.50megs.co...b450...450UPG3.asp.htm' ">http://j12345.users1.50megs.co...b450/PB450UPG3.asp.htm
http://j12345.users1.50megs.co...b450...450LAY2.asp.htm' ">http://j12345.users1.50megs.co...b450/PB450LAY2.asp.htm
 02/18/2005 09:15 AM
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KachiWachi
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My girlfriends sons old PC was a Legend 1920 Supreme MultiMedia (PB430 motherboard), and we had both a DX2-66 and the P24-T in it. The motherboard cache was upgraded to 128KB from none (I could never find the 512KB chips). I also could never find the MT4C16257Z Video RAM upgrade. System RAM was maxed out at 64MB FPM. It ran Win98SE, but slowly, since the HDD interface was limited to PIO-0. The BIOS was upgraded to allow the use of a larger 8.4 GB HDD using the MicroFirmware P4HS10 Flash BIOS Daughterboard. We installed a USR 56K ISA FAXMODEM (not the Winmodem) into the machine and it worked just fine....much better than surfing the web at 2400bps!

I still have it here...and it runs just fine!

http://www.uktsupport.co.uk/pb/mb/430.htm' ">http://www.uktsupport.co.uk/pb/mb/430.htm

-------------------------
KachiWachi

Moderator - Wim's BIOS

CPU #1 - DFI 586IPVG, K6-2/+ 450 (Cyrix MII 433), 128MB EDO. BIOS patched by Jan Steunebrink.
CPU #2 - Amptron PM-7900 (M520), i200 non-MMX, 128MB EDO
CPU #3 - HP8766C, PIII-667, 768MB SDRAM
CPU #4 - ASUS P3V4X, PIII-733, 256MB SDRAM
CPU #5 - ??? ;)
 02/18/2005 04:52 PM
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Charlie22911
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thanks a billion! i will go try the 33Mhz thing now that i know what jumper it is. oh, my board dosnt have any cache, how much does that tend to cost?

***EDIT***

HA i hit 66Mhz! is anything faster possible?

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

Laptop:
Core i7 2960xm @ 4.2Ghz | 4x4GB Kingston DDR3 1866 | 2x GTX 580m SLI OC 725/1450/1500
 02/18/2005 05:58 PM
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eddaweaver
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The performance cost is fairly high for not having cache on a 486 system. I'm surprised that it'd have none, usually they had at least a token quantity. No little black socketed modules with writing on them?

If you mean to buy, I don't know, because availability is the issue. It would've probably been difficult to buy new cache modules for 486 motherboards after 1997. It'd be easier to obtain a dead 486 motherboard and pull its cache modules out if they're socketed. This motherboard supports up to 512kb, which is a reasonable quantity (though some support 1mb).

Please watch out for heat, as a 33% overclock of a 5v CPU is going to run hot
 02/18/2005 07:16 PM
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KachiWachi
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Charlie - the U16, U19, U29, U32 and U55 are empty? What about U57 and U58?

You probably will have a hard time finding those as they are obsolete. I got mine out of scrap motherboards that were being thrown away where I used to work.

Do you have the Video DRAM ZIP in U26 and U27?

-------------------------
KachiWachi

Moderator - Wim's BIOS

CPU #1 - DFI 586IPVG, K6-2/+ 450 (Cyrix MII 433), 128MB EDO. BIOS patched by Jan Steunebrink.
CPU #2 - Amptron PM-7900 (M520), i200 non-MMX, 128MB EDO
CPU #3 - HP8766C, PIII-667, 768MB SDRAM
CPU #4 - ASUS P3V4X, PIII-733, 256MB SDRAM
CPU #5 - ??? ;)
 02/18/2005 08:34 PM
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Charlie22911
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all the of the sockets are empty, zip sockets are empty to. i superglued an old K6-266Mhz heatsink to the 486 so no worries for heat! i noticed the video chip gets pretty warm as well as the 1Mb videoram, is that from the FSB increase?

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

Laptop:
Core i7 2960xm @ 4.2Ghz | 4x4GB Kingston DDR3 1866 | 2x GTX 580m SLI OC 725/1450/1500
 02/18/2005 11:06 PM
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eddaweaver
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I suppose they could become hotter from running on a higher FSB, but the motherboard is specified to run at 33MHz, so it should be designed to be ok at that speed.

So the chip is stable at 66MHz?
 02/19/2005 03:30 AM
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KachiWachi
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Charlie -

I have plenty of 32Kx8 15nS TAG and SRAM chips for 128KB of cache... the U16, U19, U29, U32 and U55. I don't have the U57/U58 "dirty bit" TAG chips however (64Kx1). I don't know if this one is necessary though...perhaps someone else on the board can provide more input on that.

http://j12345.users1.50megs.co...b450...450UPG3.asp.htm' ">http://j12345.users1.50megs.co...b450/PB450UPG3.asp.htm

-------------------------
KachiWachi

Moderator - Wim's BIOS

CPU #1 - DFI 586IPVG, K6-2/+ 450 (Cyrix MII 433), 128MB EDO. BIOS patched by Jan Steunebrink.
CPU #2 - Amptron PM-7900 (M520), i200 non-MMX, 128MB EDO
CPU #3 - HP8766C, PIII-667, 768MB SDRAM
CPU #4 - ASUS P3V4X, PIII-733, 256MB SDRAM
CPU #5 - ??? ;)
 02/19/2005 04:45 PM
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eddaweaver
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there is plenty of dirty information here:

http://groups.google.ca/groups...+%22...G=Google+Search' ">http://groups.google.ca/groups...=en&btnG=Google+Search

It appears to be non-compulsory, but I don't know
 02/19/2005 05:55 PM
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Charlie22911
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yeah the chip is very stable, no probs at all, i wish i could try for higher speeds... 30Mb/s is all the bandwith on those cache!? i hate to see the ram banwith . i know that a VERY large preformance hit occurs when you dont have cache (ha, just turn it off in the bios) so i think finding some cache would be wise. some would think 'why go through the trouble' but i have a piece of working history and im keeping it, the HDD dosnt even have 1 bad sector on her (410Mb)!! kachiwachi, would you be willing to give up those cache chips?

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

Laptop:
Core i7 2960xm @ 4.2Ghz | 4x4GB Kingston DDR3 1866 | 2x GTX 580m SLI OC 725/1450/1500
 02/19/2005 07:18 PM
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eddaweaver
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well removing the J29 jumper appears to set the multiplier to 3x, but it could be a risk to try a 50 to 100MHz overclock, on a 5volt vcore CPU no less.

When the J25 jumper is on 1-2, the FSB is at 25MHz, and when on 2-3, the FSB is at 33MHz. Perhaps removing the J25 jumper sets the FSB to 20 or 40MHz.
 02/19/2005 07:36 PM
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Charlie22911
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the j29 jumper has no pins, just sodder points, even when i do connect them there is no chance in clock speed. also removing the j25 jumper just changes back to 25Mhz FSB.

-------------------------
Desktop:
Phenom II x6 1055T @ 4GHz | 4x2GB Patriot DDR3 1600 @ 2000 | 3x AMD Radeon HD6970 Crossfire

Laptop:
Core i7 2960xm @ 4.2Ghz | 4x4GB Kingston DDR3 1866 | 2x GTX 580m SLI OC 725/1450/1500
 02/19/2005 11:40 PM
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eddaweaver
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Here is a DX4-100 OverDrive for $3.49 shipping-inclusive, if Ebay is an option:
http://cgi.ebay.com/ws/eBayISA...iewI...ssPageName=WDVW' ">http://cgi.ebay.com/ws/eBayISA...0&rd=1&ssPageName=WDVW
http://cgi.ebay.com/ws/eBayISA...iewI...6745365247&rd=1' ">http://cgi.ebay.com/ws/eBayISA...4&item=6745365247&rd=1

I don't know whether the different pinout on the i486DX4ODPR-100 vs the i486DX4ODP-100 would be an issue, but I doubt it.
You an can easily identify a DX4-100 OverDrive CPU because the heatsink is integrated into the CPU package.

The AMD 5x86 133MHz with voltage regulators are pretty rare, but there's one for sale at the moment:
http://cgi.ebay.com/ws/eBayISA...iewI...6743964703&rd=1' ">http://cgi.ebay.com/ws/eBayISA...2&item=6743964703&rd=1
It would be the best you could put in this computer. There isn't a 100% assurance it'd be compatible, but it'd be surprising if it wasn't.

You could try setting that voltage jumper (that supposedly doesn't work) to 3.3v and see whether it fails to boot the current CPU, as that should indicate it's working.
You can get a 5x86 fairly cheaply if so:
http://cgi.ebay.com/ws/eBayISA...iewI...6745472480&rd=1' ">http://cgi.ebay.com/ws/eBayISA...2&item=6745472480&rd=1

Is the computer able to play Mp3s at 66MHz? I know a DX33 can, but in Dos.
 02/21/2005 08:02 AM
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KachiWachi
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Looks like you are stuck then with only 25MHz and 33MHz. J25-2 must go to the clock speed select pin, while J25-1/3 must be ground/pull-up (not sure which is which). With no J25, J25-2 floats, and is not enough to register as either pulled-up or ground, so you get whichever makes the bus run at 25 MHz.

What clock chip is on the board? Never mind...I saw...will look into it.

Did you try setting the thing up as a 486DX/4-100(120) per http://j12345.users1.50megs.co...b450...450UPG2.asp.htm' ">http://j12345.users1.50megs.co...b450/PB450UPG2.asp.htm ?

Did you see Note #4?
"Revision D and G Motherboards do not have J29."

Perhaps the board is hard-wired someplace as 1-2 or 2-3. Most likely as x2 (2-3). It's either that, or the installable CPUs have enough internal pull-up/down to force a multiplier non-overclock, and that's why they determined that J29 was no longer necessary (cost savings).

I'll look for the chips. Not sure where they are though. If I find them, I'll trade you for the stuff we e-mailed about earlier.

-------------------------
KachiWachi

Moderator - Wim's BIOS

CPU #1 - DFI 586IPVG, K6-2/+ 450 (Cyrix MII 433), 128MB EDO. BIOS patched by Jan Steunebrink.
CPU #2 - Amptron PM-7900 (M520), i200 non-MMX, 128MB EDO
CPU #3 - HP8766C, PIII-667, 768MB SDRAM
CPU #4 - ASUS P3V4X, PIII-733, 256MB SDRAM
CPU #5 - ??? ;)
 02/21/2005 08:39 AM
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KachiWachi
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OK...

Your clock chip is an ICS AV9154-26. -> http://www.icst.com/pdf/ics9154a.pdf' ">http://www.icst.com/pdf/ics9154a.pdf

It looks like this chip can provide CPU clocks from 7.88MHz to 50.11 MHz...if jumpered correctly.

25MHz = FS(2:0) is 3 = J25 1-2
33MHz = FS(2:0) is 2 = J25 2-3
40MHz = FS(2:0) is 1 = J25 ???

It looks like J25 controls FS0, while FS1 is hardwired to a "1". In order to get 40 MHz, you'll need to make FS1 a "0", then jumper for 25MHz. This will require surgery to the motherboard.

FS0 = pin 1
FS1 = pin 16
FS2 = pin 10 <- we don't care about this pin
* all are internally pulled-up

Freq. FS0 FS1 FS2
40MHz = X O O
33MHz = O X O
25MHz = X X O

-------------------------
KachiWachi

Moderator - Wim's BIOS

CPU #1 - DFI 586IPVG, K6-2/+ 450 (Cyrix MII 433), 128MB EDO. BIOS patched by Jan Steunebrink.
CPU #2 - Amptron PM-7900 (M520), i200 non-MMX, 128MB EDO
CPU #3 - HP8766C, PIII-667, 768MB SDRAM
CPU #4 - ASUS P3V4X, PIII-733, 256MB SDRAM
CPU #5 - ??? ;)
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