IBM PS/1 2155 78C CPU Upgrade Advice \ VOGONS

IBM PS/1 2155 78C CPU Upgrade Advice

Topic actions

Post a reply

First post, by HoneyBadger1650

Posted on 2017-09-22, 18:38

Rank Newbie

Rank: Newbie
Posts: 12
Joined: 2017-09-22, 18:21

Hello all,
I've got an IBM PS/1 machine that originally had an Intel 486sx2 processor in it, but was at some point upgraded to a 66MHz Pentium OverDrive (which is what it's running right now). I'm now wanting to upgrade it further, and am left stuck deciding whether or not I should upgrade it with an Evergreen 586 (essentially an AMD Dx5 cpu) clocked at 133 MHz, or a Cyrix (Cyrix GXm-200GP GX Media MMX CPU). I also saw a PNY QuickChip for sale (all on eBay) which is essentially the same as the Evergreen, but I felt like the Evergreen would be the better of the two. I'm completely new to these types of computers, so I really have no idea what the best option is.
PS: System's memory is maxed out at 64MB, it's using a CF card instead of a mechanical HDD, so data transfer's most likely maxed out to the speed of the IDE controller, and there's no TAG or L2 memory installed on the board. Probably will install some at some point though. Let me know if i need to give any more info.
Thanks in advance!

Reply 1 of 3, by jade_angel

Posted on 2017-09-22, 18:49

jade_angel Offline

Rank Member

Rank: Member
Posts: 359
Joined: 2017-01-03, 00:10
Location: Virginia

I'm pretty sure that, while the MediaGX is essentially a Cx5x86 core, it cannot be used in a Socket 3 motherboard. That leaves the Am5x86 as a possible upgrade path (or the Cyrix Cx5x86/120, OC'd to 133, or similar). The AMD CPU is going to be a little faster than the POD/66 for integer math, and probably about the same or a little slower for floating point (the Pentium's FPU is considerably better than the 486's).

See feipoa's thread here The Ultimate 486 Benchmark Comparison for more info on the various upgrade options.

Main Box: Macbook Pro M2 Max
Alas, I'm down to emulation.

Reply 2 of 3, by lazibayer

Posted on 2017-09-22, 19:32

lazibayer Offline

Rank Oldbie

Rank: Oldbie
Posts: 1065
Joined: 2014-10-21, 21:16

Is it 83MHz or 63MHz? POD doesn't have a 66MHz release AFAIK. OC it to 40x2.5 and you will get pretty solid FPU performance.

Reply 3 of 3, by HoneyBadger1650

Posted on 2017-09-22, 20:57

HoneyBadger1650 Offline

Rank Newbie

Rank: Newbie
Posts: 12
Joined: 2017-09-22, 18:21

lazibayer wrote:
Is it 83MHz or 63MHz? POD doesn't have a 66MHz release AFAIK. OC it to 40x2.5 and you will get pretty solid FPU performance.

It's 63MHz, sorry I was thinking of what I saw on CPU-Z. I'm probably going to go with the AMD 5x86 route with the Evergreen chip, but just out of curiosity, how would I overclock the POD? I know that some motherboards had jumpers that you could set and it would change the (correct me if I'm wrong) bus speed?. This motherboard has jumpers for an SX and DX setting (2 separate jumpers that both say SX and DX), and both of those are set to the DX setting, and then there's an unlabeled jumper which is also set to DX (I looked on this site http://stason.org/TULARC/pc/index.html for the motherboard info, and it's set correctly), but there aren't any other jumpers that can be set for a clock speed increase. Not to my knowledge at least.

Go to top of page Go to top of page

Back to General Old Hardware

Main menu

Common searches