Upgraded CPU=slower boot?

Posted by Aurilion_DeSilva@reddit | vintagecomputing | View on Reddit | 14 comments

Hey all. I have a Digital PC 3100 (DEC). 166mhz pentium mmx installed, 64mb ram, 430tx chipset. Bit yellow, but otherwise a lovely machine to use and work on. Currently running Windows 95 osr 2.1, and cold boots to desktop in around 25 seconds.

Recently upgrade the machine to a 233mhz pentium mmx. Changed the dip switches to configure, and everything is recognised fine. Updated the bios to v1.12 (latest) prior, which does list 233mhz intel processors as supported.

However when I start the machine now, its probably closer to a 50 second start, despite the faster CPU. The hold up occurs after post on the summary screen, before the Windows boot spash screen occurs. Theres no apparent hard drive activity during the wait - just a blinking cursor.

Once it boots though, it runs like a dream. No weird slowness or anything. Its actually been a really nice upgrade otherwise. Currently enjoying some tiberian sun!

Does anyone know why the machines boot time has doubled? Im at a bit of a loss...

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Aurilion_DeSilva@reddit (OP)

Thanks for all the comments. I did some more testing after work today and actually figured it out while looking at the boot order. I had boot from floppy selected as the first entry, and when I'd put the system back together after the upgrade I must've forgotten to plug the drive back in. It would have been trying to find the drive for 20ish seconds during boot, failing, then booting windows. Whoops!

Plugged the drive back in - problem solved!

bnelson333@reddit

Probably the fast RAM check reset to slow as others have mentioned. Another possibility: if it has onboard LAN and it was disabled before and is now enabled in BIOS, if you don't have it plugged into a network with a DHCP server, it adds a significant delay to bootup while it waits to see if it can get an IP. If this is the case, either disable the onboard NIC in the BIOS or plug it into your network.

cjc4096@reddit

Slower bus resulting in longer mem test? Check the multipliers between the 2 cpus.

LittlePooky@reddit

My desktop (that I am using to write this) is i9 14900k with 64 G of RAM (Windows 11 for Workstations). It feels fast considering I upgraded from Intel i7 with 16 GB a year or so ago,

But I do have a few hard drives connected to it, and that takes a while for the computer to come up. I wonder if that's your case too.

Mine too once it's running, there's no stopping it.

fiasn@reddit

I seriously doubt the issue is the same on your i9 desktop as it is with this dudes Pentium MMX system dude

LXC37@reddit

Actually i9 or p166mmx does not really matter and while it might not necessarily apply to OPs situation - the idea is correct. Each added device takes time to initialize so adding any extra hardware, be it HDDs, USB stuff, memory, expansion cards, etc, etc will always increase boot time. And no, added hardware does no have to be in any way related to boot process - it gets initialized anyway.

My external hard drives, and I have 8 of them, connected to 2 different Direct Attached Storages. I wondered if it would speed up the startup of Windows, so I turned off the power to both, and it made a huge difference.

bhiga@reddit

That's USB device scanning, but the system in question likely doesn't have USB, and even if it does, even less likely it supports booting from it, so it wouldn't have the scan delay.

Accurate_Estimate811@reddit

I wonder if it's counting Ram or something

DominantDan24@reddit

That was the first thing I was going to suggest: the BIOS is probably doing a memory check, which typically chews up 20-30 seconds.

2raysdiver@reddit

That is something you can turn off in BIOS, and something I've seen get reset when swapping CPUs.

Scoth42@reddit

I'd wonder if the BIOS upgrade either added some additional hardware checks or otherwise changed/reset some settings that is slowing it down. Floppy Drive Seek At Boot is one that can add a bit as it churns the drives. Might check all the cache and memory speed settings if there are any in there.

Maybe try temporarily putting the 166 back in and see if that makes a difference?

yeah thats a good idea actually. throw the 166 back in and see if it still takes as long, if it does, id just chalk it up to the updated bios with more hardware checks and call it a day.

bigbigdummie@reddit

Your 233 should run at 166. Just flip the switches and see what happens.