Aluminum (?) pad between Pentium MMX and heatsink

[Ed Herdman]

Yes, that Pentium. Here's a real trivia question for you folks.

Along with all the other spring cleaning and reorganization underway, I decided to give the faithful old Packard Bell (with a brand-new-for-1997 Pentium MMX) some love. Still got some of its factory fresh smell inside, but there was still a tiny bit of dust in spots, a bit of grime on the case, and I also had some other objectives in mind (such as: How do you tear this infernal thing down when you need to?) I also thought that it'd be a good time to replace the thermal paste, having seen how the paste in a mid-'90s Power Mac turned to chalk. But this stuff was still good. Too late to put it back, though.

Between the Pentium and the heatsink I found a little silvery plate - could be aluminum. This is most curious.

I thought that maybe this was used to smooth the transition from the CPU to the heatsink, but that doesn't make sense to me since the heatsink's mating side is not really uneven. On top of that, it's another layer for the heat to travel through and that extra distance might end up retarding the heat flow somewhat - or is this just modern thinking based on having seen too many thermal paste reviews?

My other explanation is that the application at the factory involved simply placing this piece of aluminum, with paste applied to both sides already, on top of the CPU, and then putting the heatsink on top of that.

Anybody know what's going on with it?

I still have half a mind to reverently put it back in place there, just for old times' sake...I'm sure I'll still be running afoul of Murphy's Law if I put it back in upside down, though!

[SteveNielsen]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I recently worked on a P4 with something exactly that on the CPU too. It looked and felt exactly like aluminum foil tape used for heating/ac duct work.

[Topcat]

Re: Aluminum (?) pad between Pentium MMX and heatsink

If there were wires attached to it, its known as a Peltier cooler.....which was the overclocker's cooling fad back then. if its just a silver looking pad, its bascially the same as heatsink compound.....it provided good contact between the processor and the heatsink. Ohh the memories of those days....peltiers and lapping the tops of the CPU's....anything to squeak another couple megahertz out of a slow ass CPU...

[Ed Herdman]

Re: Aluminum (?) pad between Pentium MMX and heatsink

Thanks for the responses! No peltier here. The aluminum pad is stock - I can guarantee that nobody has ever worked on this thing; I'm looking at the 1997 factory configuration (I can date it pretty well because it says March 1997 on the (Lucky) Goldstar CD-ROM drive). Another throwback: There are only two wires going to the fan on the green heatsink - and they come straight out the back of a Molex, which is itself coming directly out of the PSU. No Q-fan or PVM control here.

And there's thermal paste between the aluminum pad and the CPU - and between the aluminum pad and the heatsink. It's that redundancy that has me confused.

Model name is L90, which I guess was probably ~$2000, a "Multimedia" PC. 16MB of RAM (originally), and level transitions in Half-Life only take 8+ minutes!

And I'm derailing my own thread now, but here's some Stuff People Used To Write On Serious Websites:

PB SRAM uses Pipening

Florida International University homepage, citing the October 21 1997 issue of PC Magazine.

if you run [a Pentium II server] with more [than 512MB RAM] you got to disable both caches, L1 as well as L2!!! This results in a perfomance at Pentium 75 niveau.

Tom's Hardware, December 1997

The only problem I see here is getting the Pentium MMX stable at 290.5MHz, when testing it, the system crashed a few times however I believe most of the crashes were caused by inefficient cooling (I didn't use any thermal compound).

Anandtech, July 1997

[RJARRRPCGP]

Re: Aluminum (?) pad between Pentium MMX and heatsink

(I can date it pretty well because it says March 1997 on the (Lucky) Goldstar CD-ROM drive).

I have a GoldStar CRT from the same year and it's still going strong!

[cheapie]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I have a Packard Bell Legend 115 Supreme (with a 100 MHz Pentium), and it had the same thing. I just threw it away and put some leftover AS5 in there.

[Ed Herdman]

Re: Aluminum (?) pad between Pentium MMX and heatsink

@ cheapie: Thanks, love those old PC names...yeah, I think I'd better just go ahead and ditch it. It's doing nothing good anyway. It's not thick enough to be a spacer, I don't think.

I have a GoldStar CRT from the same year and it's still going strong!

Yeah, the reliability on everything related to this PC is great.

The only thing that's worn out from use is one of the rubber domes on the keyboard - I opened it up and found that the end of the dome on the right arrow key (of course...all those hours of Comix Zone and DOS games) has separated. I just swapped parts so that one is elsewhere.

Monitor is doing great; it's a 15" shadow mask by Proview, the 4150 model, with a mfr date of May 1998. What's with that date continually creeping upwards? This is the original monitor, I'm sure. Funny thing - we've probably had and ditched newer / better CRTs in favor of this one, but I like the shadow mask look for this PC - have enough aperture grille displays as it is.

Meets Swedish MPRII low emission standard!

[SteveNielsen]

Re: Aluminum (?) pad between Pentium MMX and heatsink

The foil I peeled off the P4 CPU wasn't wired either but it felt like it was glued on. Could've been dried thermal compound but didn't look like it. It was just as if it was a piece of aluminum duct tape.

[Heihachi_73]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I've had a Packard Bell Executive 3166D since 1997, which came stock with a Pentium 166 MMX (with a separate heat sink/fan, not the molded all-in-one CPU with the tiny HS/fan commonly found on Pentium 1 CPUs), Windows 95 (with MS Money, Word and Works 95 all pre-installed, rather than the full-blooded Office 95 in its entirety) and all of 16MB RAM, and a 2GB Seagate ST32122A HDD and a 48X Sony CDU4811 from 1999, as its original CD drive died very early in its life and was RMA'd. The video chipset was an S3 ViRGE, with 2MB built onto the board and no way of upgrading it (aside from using a PCI video card). Additionally, its only means of expansion, instead of being 4 PCI/4 ISA like a normal BabyAT desktop, was a 4 slot dual PCI/ISA riser card instead of the regular design, so not many things could be added to it, and taking up one ISA slot from the factory was with a 56K Aztech Labs AZT3013 "Winmodem"/sound card (SB Pro-based, so it sounded like crap and could only have one sound being played at a time, so if you had Winamp going or whatever, Windows itself couldn't play its error sounds over the top of it).

What can I say, I had it for about 2 years (1 year warranty, of course!) and the PSU crapped out, and ever since it's had a 1993-dated PSU borrowed from a damaged 486 (Seventeam ST-200WV, branded as an Ipex ST-200WHV).

Also, the original Packard Bell I had bought for me (I was 13-14 back in 1997) was a "Legend" model with a tower form factor, but the machine was RMA'd after it no longer wanted to power on (at a loss of everything I had at the time, mostly homework and a few game saves though), with the replacement being the "Executive" model desktop instead. Unlike from what I've heard online about Packard Bell in the "Picasso" logo era, both PCs were not old systems which had been refurbished in a new case, although a few years ago I did come across a Packard Bell 486 system with the same case and similar ISA-only riser card, but it only had a 540MB HDD or something similar.

The 3166D still lives today (as does the 486), gathering dust somewhere around the house, however its 14" monitor was scrapped a number of years ago (the monitor stand had broken after it met the floor after an accident, and it used to wobble around when you were typing!). It ended up going blurry over the years so it was thrown out when we found another monitor in the hard waste (LG 15" CRT), and by 2001 I had a new PC again since by that stage the old 166 simply couldn't keep up with anything, even though by that time it was overclocked to 200MHz, with 32MB of RAM and Windows 98 SE).

Let's just say that it couldn't keep up with a new fad just starting up at the time, video game emulation! NESticle ran OK, albeit in its buggy, early status as an emulator, and had very loud, crackly sound output, but anything else that wasn't NESticle or SNES9x was a crawl on that PC (of which my parents stupidly paid $2 for in a market back then! Let's just say that coming home to see Super Mario Kart on a floppy disk was an unusual experience; even I knew back then not to fall for pirated stuff like that! Although, I did actually have the game on Super Nintendo at the time - I was a console kid before I got into computers, my prior PCs being only a monochrome 286, ex Pizza Hut point-of-sales, and it was a POS , right down to the monitor coming on with everything half way off the side and written backwards when you powered it up, and having "Welcome to Pizza Hut" burned on the screen when you turned the brightness all the way up, and an ancient Sanyo MBC-550 which wasn't 100% PC compatible; unfortunately they were all thrown out a year after I got the Packard Bell). The PC itself was quite happy playing proper PC games like Grand Theft Auto 1 and the like, just as long as it wasn't full 3D (no Quake or Duke Nukem on this PC, although I had never actually owned Doom or the like for that matter, only ever playing them on a friend's system) - the ViRGE wasn't called the "graphics decelerator" for nothing! Probably my favorite PC game of the time, aside from GTA1, would have been Dune II on another friend's PC, however I never found the game in stores so I never got to finish it. Stupid Fremen troopers being almost the same color as Harkonnen and being hard to distinguish until they take out your guys, and that asshole sandworm killing everything else!

That PC also tried out Windows ME in the OS' heyday, but was dropped straight to 98 after about a month as it was junk, especially with only 32MB RAM! Also, the fact I had to resort to a boot disk (Win98/DOS7) to run games in pure DOS was a pain in the ass as well. GTA1 ran better in DOS than Windows, at least for me. I had also meddled around with Red Hat 6/KDE but could never get the modem working under Linux; the sound card worked OK although it was still crappy.

[eccerr0r]

Re: Aluminum (?) pad between Pentium MMX and heatsink

They used to make thermal "pads" that were based on an aluminum core, with heat sink compound on both sides. Easier to slap on one of these than to carefully apply paste...

Just for QC I think, but it does add a bit more thermal resistance...

[Ed Herdman]

Re: Aluminum (?) pad between Pentium MMX and heatsink

Just a thought: I've been wondering if changing caps on the Sound Blaster AWE64 (or some other component - maybe the PSU as well) will do anything for the rather high noise floor. But possibly the DAC is noisy, and of course the board is totally unshielded. For CD audio, there's also the classic thin gray wire fed between the sound card and the CD-ROM. Anybody have experience with that?

@ Heihachi: I was also 13-14 in 1997! Interesting data points to compare to, there. I guess that extra 33MHz really makes a difference - I had no problem playing any DOOM engine game (Ultimate DOOM titles, Heretic, Hexen) or Quake.

My system only had the 1MB S3 Virge - I never tried to run really aggressive titles on it. After a while we had a Voodoo 2 3000 - 'fraid I sent it out the door by accident inside a system we no longer needed, but still have the box at least. Classic stuff. Anyway, I never really understood the "Video decelerator" thing, since I could run Half-Life! The problem there mainly seems to be related to the under-minimum-spec 16MB RAM installed by default in the L90.

Ms Money and Works 95 sound familiar...not sure if Word was on there in a preinstallation, but I think not. We used WordPerfect 7 primarily. Other bundled software included a photo editor and a version of the classic Packard Bell Navigator software.

The motherboard has a couple smallish Sanyo capacitors on it. The riser board is also three PCI, and three ISA, in a 2-3-1 configuration, ISA at the top and bottom, lots of identical CapXon capacitors. There's six slots on the case back but I don't think you'd really be able to fully populate it; still, I could mix up some ISA and PCI stuff on there. I already mentioned the stock Aztech combo soundcard / modem.

2GB hard drive - not cheap in 1997.

They used to make thermal "pads" that were based on an aluminum core, with heat sink compound on both sides. Easier to slap on one of these than to carefully apply paste...

Just for QC I think, but it does add a bit more thermal resistance...

Thanks for that. My second guess was on the right track, then.

[ratdude747]

Re: Aluminum (?) pad between Pentium MMX and heatsink

Yeah, that's a compound replacement pad. They are commonly found in OEM builds (pentium M laptops too)... and submersion type OC rigs (since the oil in the tank would leech traditional compound.

[Heihachi_73]

Re: Aluminum (?) pad between Pentium MMX and heatsink

Sounds like mine... Doom runs fine on it today, and on my older 486 systems as well (all DX2 66 or DX4 100MHz), it's just that I never had the game back in the 90s since I had a number of consoles instead - never played many PC games aside from GTA1, unless NetHack on the 286 counts.

I also have the original Spear of Destiny on 6 5.25" floppies these days, found it in a thrift shop in 2006 or so and it was only $2 with everything, even the original sales receipt from 1992 was still in the box!

I can remember the Packard Bell Navigator by name, never used it though (it vanished after the HDD was formatted and had 98 installed). Also, it was the era where MOD files were popular, so naturally I had a MOD tracker installed - Fast Tracker 2 it was for me back then, complete with its own updated .XM format.

[RJARRRPCGP]

Re: Aluminum (?) pad between Pentium MMX and heatsink

f you run [a Pentium II server] with more [than 512MB RAM] you got to disable both caches, L1 as well as L2!!! This results in a perfomance at Pentium 75 niveau.

Not all of that even makes sense, the northbridge has nothing to do with L1.

Sounds more like a buggy board.

[kaboom]

Re: Aluminum (?) pad between Pentium MMX and heatsink

For CD audio, there's also the classic thin gray wire fed between the sound card and the CD-ROM. Anybody have experience with that?

Those were good for induced currents on the two inner signal wires, caused by a sort of ground loop.

The shield of that cable connects at both ends, which weren't always at the same potential despite being commons.

Current from the M/B could go back to the chassis (or vice versa), via the sound card, cable, and drive frame. As this current had sharp transitions, it had an AC component from on end of the shield to the other. This induced, as it was passing them, noise in the two signal wires.

If you've ever noticed a large decrease in noise when muting "CD In" in the mixer, this is why. Yes, there could be a noisy DAC in the drive where the CDDA comes from, but this ground loop was often substantial in lots of PCs.

You can break the shield of the cable at the sound card, and put a resistor in series- a "loop breaker." Anything from 10 to 47 ohms.

The actual return path will then mostly be through the chassis (back to the drive), and a little through the resistor. You might also have to put two 22-33 ohm resistors, one in each channel, in each signal lead at the sound card. Most of the time, this is a high-ish impedance path so little loop current flows here. The shield/common is where most trouble came from, though.

[AnuPB]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I have a Packard Bell Platinum 1, which has the same thing on the 133mhz NON MMX processor. I believe it is the thermal paste, because I see some under the part of the sticker not touching the CPU.

[momaka]

Re: Aluminum (?) pad between Pentium MMX and heatsink

Model name is L90, which I guess was probably ~$2000, a "Multimedia" PC. 16MB of RAM (originally), and level transitions in Half-Life only take 8+ minutes!

Ah Half-Life, what a classic! Funny you mentioned this. I just started playing it again 2 weeks ago after feeling a little nostalgic. I remember back in early 2000 when I first played that game with my friend on his Pentium II PC. The PC itself was probably more than capable to run it well in 3D, but we didn't know much at the time (were were maybe 10 or 11) so it was playing in Software Render mode. As you might imagine, that was quite crappy... but I still remember that experience of us screaming hard and scared s***less when we got attacked by those aliens for the first time (ironically, we first tried this game out on a late Saturday night and we didn't have lights in the room). Fun times!

As far as retro computers, the most ancient thing I still have so far is some socket 7 Compaq motherboard with either a 133 or 166 MHz Pentium MMX, 32 MB onboard memory, and onboard 1 or 2 MB S3 Trio64 video (or maybe it was a Virge, I don't remember). Also has onboard audio driven by ESS AudioDrive chip (read: crappy sound). The system itself has only 1 PCI and 2 or 3 ISA slots. A single slot for SDRAM is also provided. Caps on the motherboard? Several I.Q., but the CPU has a two green Sanyo caps as well. The rest is all tantalum. I found this PC on the side of the road way back in 2004. Took the motherboard out of the case for a cleaning, but then didn't put it back in right away. My parents didn't know and threw away the case away, so now I only have the motherboard, PSU, and HDD. Speaking of which, the HDD was a 3.2 GB Quantum Bigfoot. That works too, but occasionally gets its heads stuck on the platters so you have to bang it a little to start it .

Another ancient system I had but never got to testing (also found on the side of the road) was a Gateway P5-100. AFAIK, that was an even older system. What a shame.

Yeah, that's a compound replacement pad. They are commonly found in OEM builds (pentium M laptops too)

Yup. My Dell C-series laptops have them on their chipsets. Possibly the CPU as well, but I don't remember for sure.

BTW, thank you, Kaboom, for your informative post above! Very useful info.

[lti]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I still have a 200MHz Pentium MMX and a dead motherboard from an old Gateway computer. It had a hard gray thermal pad, which appeared to be one of the graphite-based pads.

I still use a Compaq Presario 2286. Its CPU replacement instructions say to use a "thermal transfer crayon" instead of a thermal pad. I guess they're talking about this. I just used some really crappy paste when I put a K6-2 in it. If I ever get some money (which is unlikely ), I might put a video card in it and try to repair the Gateway motherboard.

I wonder what the weird white and blue foam-looking pad in my Gateway Solo 2500 was.

[Heihachi_73]

Re: Aluminum (?) pad between Pentium MMX and heatsink

I have plenty of AT Socket 7 systems, mostly generic beige cases though, not brand names.

Surprisingly, the Packard Bell has Sanyo OS-CON caps on the board rather than cheap no-name electrolytics.

[TELVM]

Re: Aluminum (?) pad between Pentium MMX and heatsink

... Between the Pentium and the heatsink I found a little silvery plate - could be aluminum. This is most curious ...

I once found a paper sticker on the IHS of a K6-2, something like this ...


... only even worse, as the sticker was more centered. Oh and no paste of course. Most amazingly that K6-2 is still alive & kicking (minus sticker).


Just remove that useless plate, clean thoroughly both IHS top and heatsink base, and apply some decent thermal paste.