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Upgrade Pent II in my DIGITAL PC 3500/5510

ColorComputerStore

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Sep 23, 2017
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194
I have a DEC DIGITAL PC 3500/5510. It has a 300Mhz Pentium II. The motherboard is based on the Intel 440LX chipset.

The service manual covers the processor clock speed switch settings.

It lists the following speeds:
133
166
200
233
266
300
333
366*
400*
433*
466*
500*
533*
*Reserved for future use

I was told the fastest Pent II I could use would be a 333. Considering I have a 300 now, that isn't such a nice jump.
I have seen Pent II for sale as reasonable costs up to 400MHz. But I am unsure if I can in fact go above 333.

I have conflicting information on whether I could also use a Pentium 3 slot 1 as an option.

Finally, some folks recommended a Celeron with a slot 1 adapter. Although the cache is smaller the speed is faster on the Celeron.

I am using the machine for DOS, Win 95 and Win98 games. Not really 3D FPS... more of RPGs and RTS games. I do have the RAM maxed out and a Rage 128 card.

Should I just leave the CPU alone considering what I use the machine for? Or should I spend a little cash and upgrade the CPU?

I'm very curious about the 'Reserved for future use'. Hate to buy a faster CPU and it not work. hmmm..
 
The 440LX can only do an FSB of 66 MHz, which limits the supported processor speed. If I remember correctly, the Pentium II had an FSB lock-out "feature" that will prevent any CPU for an FSB of 100 MHz to even work at 66 MHz, so you can not use e.g. a 400 MHz one.

The early Pentium III with the Katmai core will work as a direct replacement for a Pentium II. The mainboard/bios does not need to have any support for it, as it's just a Pentium II with SSE and a serial number added. This won't really help you, however, as there was no Pentium III for 66 MHz FSB.

A socket 370 adapter may help, not sure. Never messed around with these.
 
100MHz FSB P2s will run just fine at 66MHz FSB. The multiplier is locked so they simply run at a lower speed. E.g. the 400MHz rated processor will run at 266MHz
 
Kinda getting lost. What are the recommended options for faster speed from my 300MHz Pentium II then?
Am I hearing... Pent II 333MHZ, any Pentium III and Celeron A as the options?

cheers
 
Kinda getting lost. What are the recommended options for faster speed from my 300MHz Pentium II then?
Am I hearing... Pent II 333MHZ, any Pentium III and Celeron A as the options?

cheers

there's not a whole lot you can do unless you can find an engineering sample with an unlocked multiplier
 
Kinda getting lost. What are the recommended options for faster speed from my 300MHz Pentium II then?
Am I hearing... Pent II 333MHZ, any Pentium III and Celeron A as the options?

cheers

If you check the Wiki here's what you get for the Pentium II:
233 MHz to 450 MHz
FSB speeds66 MHz to 100 MHz
The chipset; i.e., the Intel 440LX only supports the Pentium II. Unless you're dealing with a Slot 1 mobo, the Pentium II Pro/Overdrive (450 MHz) is a Socket 8 (387 pins). Everything you ever wanted to know about the Pentium II: http://datasheets.chipdb.org/Intel/x86/Pentium II/24333503.PDF
 
Slot 1 celerons go up to 433MHz. PPGA ones go up to 533MHz but would require an adaptor. Or maybe you could do a 600MHz Katmai underclocked to 400MHz. All in all, there's not a whole lot of room for improvement when you're stuck with 66MHz FSB.

Any overclocking options on that thing?
 
They used to sell "slotket" adapters that supported the later "Coppermine" pinout for Socket 370, which let you stick Pentium IIIs and Celerons in older motherboards. They had a hit-and-miss reputation for reliability and compatibility but *if* you can get one to work you could theoretically go as high as 766mhz with a 66mhz bus Coppermine Celeron. The gotchya I think you'll run into is unless you find a slotket with an onboard VRM (which I think *may* have existed, there are references to Powerleap products out there that sound like they fit the bill) there's a good chance the VRM on your motherboard won't support the lower voltage for Coppermine CPUs. You may also have BIOS issues with a chip that supports SSE.

There are forum posts out there claiming success with this kind of upgrade, but you'd be a lot better off with a 440BX as the foundation of an overly tricked-out Pentium II-era machine.

EDIT: Googling around, yes, PowerLeap sold upgrade packages built around a Slotket with a VRM. In theory you might be able to go as high as 924mhz by using one of their VRM-equipped adapters paired with a 1.4 Ghz(@100mhz FSB) Tulatin Celeron-T. Suspect you'd probably either need to be extraordinarily lucky or pay through the nose to get the parts, though. PDF describing said package.
 
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Slot 1 celerons go up to 433MHz. PPGA ones go up to 533MHz but would require an adaptor. Or maybe you could do a 600MHz Katmai underclocked to 400MHz. All in all, there's not a whole lot of room for improvement when you're stuck with 66MHz FSB.

Any overclocking options on that thing?

good call I totally forgot about the Mendocino celerons, that would be the thing to do
 
good call I totally forgot about the Mendocino celerons, that would be the thing to do

That would certainly be the most *reasonable* upgrade, anyway. A "dumb" slotket without a VRM will do the job (unlike the Coppermine), the 128k cache is usually adequate (contemporary benchmarks bear out that the increase in MHZ more than cancels out the larger cache of a 66mhz Pentium II), and there are fewer BIOS gotchyas. Going the full Celeron-T+VRM route is gross overkill unless you literally have the parts sitting next to you.
 
Still over my head...

If I somewhat follow, I would buy a "Socket PPGA 370 to Slot 1 CPU Daughter Adapter Card":
https://www.ebay.com/itm/New-sealed...032324?hash=item365ef02c84:g:Gf0AAOSwjLZd3aIT
and then buy a Socket 370 Celeron. And as for the Celeron, I would still need to make sure it is one of the listed speeds I posted to my original post? (or any Celeron is fine?)

How about something simple of just going from my 300MHz to a 333MHz Pentium II? Any noticeable speed increase?

Thanks for helping this Wintel newbie.

Carlos
 
If I somewhat follow, I would buy a "Socket PPGA 370 to Slot 1 CPU Daughter Adapter Card":
https://www.ebay.com/itm/New-sealed...032324?hash=item365ef02c84:g:Gf0AAOSwjLZd3aIT
and then buy a Socket 370 Celeron. And as for the Celeron, I would still need to make sure it is one of the listed speeds I posted to my original post? (or any Celeron is fine?)

So far so good:

The link you posed is an example of a "simple" slotket without a voltage regulator. That should be fine for Celeron CPUs up to 533mhz. The voltage regulator in your machine probably does not support the lower voltage needed for "coppermine" CPUs so 533mhz is going to be your hard limit. Be a little careful if you specifically shop for a 533mhz Celeron because I believe that came in both "Mendicino" and "Coppermine" versions; the Mendicino, the one that works, has a brown-ish package with a metal cap on it and the socket pins are visible from the top, while the Coppermine is blueish-green and has a "naked" CPU core potted to the top of it.

Here's the cheapest route I see on eBay to get you up to 533mhz. Dumb jumperless Celeron-only Slotket for $12+$4 shipping:

https://www.ebay.com/itm/NEW-SOCKET...S-NO-JUMPERS-NOT-FOR-PENTIUM-III/324094407759

A 533mhz Celeron for $15+$4:

https://www.ebay.com/itm/Intel-Cele...ket-370-FV524RX533-CPU-Processor/253643371463

And you'll have to find a CPU fan somewhere for a few more bucks. If you're willing to settle for 466mhz or 500mhz you could cut the CPU price in half.

Going from 300mhz to 333mhz probably wouldn't be humanly perceptible. The jump to 466mhz-533mhz is probably "worth it", although that comes with the proviso that we're talking about the sort of difference that might solve the occasional slowdown in games that otherwise run decently well; pretty much anything you do to that computer won't move it to the "next level".

(The really fast Celeron CPUs like the 766mhz 66mhz Coppermine and the 1.4mhz 100mhz Tulatin were generally criticized for simply having too much of a mismatch between bus and CPU core speed to really make speed bumps past a certain point work, at least with their relatively small caches. 533mhz is probably right about at the inflection point into diminishing returns.)
 
I though all the cu-mine celerons used 100MHz FSB (while the P3s had jumped to 133)

They came in both flavors. The ones up to 766mhz were still 66mhz, 800mhz and faster were 100mhz. (Cu-mine Celerons went up to 1.1Ghz, 1.2-1.4Ghz were Tualatin and had twice the cache but stuck with 100mhz.)

(Editorially speaking the 66mhz versions really were junk, at least compared to AMD's offerings of the time. A Duron would run rings around them. The 100mhz ones weren't quite so bad but still pretty inferior given the Duron's better FPU.)
 
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If you have most of the hardware you need on-hand, and are convinced that this is the way you want to go, then you need not take much stock in the following. However, for a few more bucks and a little searching you might be able to score a Super Socket 7 and drop a K6-2 or K6-III in it and have a real nice gamer, and you'd get AGP to boot. I don't particularly care for Slot 1. The why is because we had them in the workplace for a while and the reliability wasn't very good (Dell). Doesn't mean if you decide to go ahead with your Slot 1 that you would need to hold your breath everytime you power up. My Super Socket 7 was one of last years' projects and it's still up and running very nicely. Good luck with your project.
 
When you put in a Socket 370, aka https://www.ebay.com/itm/NEW-SOCKET...S-NO-JUMPERS-NOT-FOR-PENTIUM-III/324094407759 with this device
It snaps in the same way as the Pentium 2 does? The socket adapter is just a bare PCB board. Wasn't sure if I need to also replace the method to hold this device onto the board.

Hmmm... this is a tough one... The outside of the machine says 'Pentium II'. I'd like to try to keep it to the original equipment as much as possible. Maybe I should forget the Celeron?.. just get a Pentium II 333MHz. Call it a day.
I have a Celeron board already to build a system and already working Pentium 4s, some 8088s, some 286s and 486s systems... so my collection is pretty much covering all of Intel's CPU eras. Might be best to leave this machine as Pentium II class.

I suffer from that problem of expand every machine I get to its max vs keeping the machine somewhat original and enjoying the limitations of each... while having a variety of machines to 'play' with. lol.
 
When you put in a Socket 370, aka https://www.ebay.com/itm/NEW-SOCKET...S-NO-JUMPERS-NOT-FOR-PENTIUM-III/324094407759 with this device
It snaps in the same way as the Pentium 2 does? The socket adapter is just a bare PCB board. Wasn't sure if I need to also replace the method to hold this device onto the board.

Generally these devices came with a couple little plastic clips to shove into the top of the slot retainer bars to help hold them in; if the one in the listing I threw out is missing them then, yeah, maybe you might want to look at some others that have them. (That $20 listing for the sealed box does seem to have them and has free shipping so, sure, maybe it's a better buy.) You don't necessarily *need* those clips, but it is true that if you don't do anything to keep the card from creeping out it may well do so over time thanks to thermal cycling.

As I said, I don't see any point wasting money on a 333mhz Pentium II if you already have a 300mhz, you'll never notice the difference, but if it's something you want to do just because you can the option is certainly there. As for the "label being wrong" if you shove a Celeron in there I suppose that depends on how you define "Pentium II". The original (and terrible) natively Slot I Celerons were literally the same CPU die as you'll find inside a 233-333mhz Pentium II, they just left the L2 cache chips off. The 300-533Mhz "Mendocino" Socket 370 Celerons we're talking about for this upgrade are, featurewise, that core with a 128K of L2 cache stuffed on the same piece of silicon. So for any program that doesn't specifically look at the CPUID bits they are also, in every way that counts, a "Pentium II". So, really, the argument boils down to "what do I want to see when I take the lid off?".

(And finally, if you *really* want to confuse matters, the "Dixon" Mobile Pentium II that appeared briefly in laptops before Intel went all-in on the Pentium III is a Mendocino Celeron core with 256K instead of 128K. The 400mhz version of that actually has the highest benchmark scores of any Pentium II ever made, so technically speaking the best Pentium II was actually a Celeron.)

But, realistically, if you already have a Celeron machine and otherwise are covered then there's no point upgrading this machine at all.
 
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