I don't know what Intel was up to

[Shocker]

I got an old desktop case with an Intel D865GLC in it.

The main aspect that interests me is that it's new enough to have SATA ports and dual-channel RAM, but old enough to use leaded solder.

But there's a catch.

12V input is 4 x 1200uF Chemi-con KZEs. Vcore output is 7 x 680uF 2.5V Chemi-con PSAs and 3 x 820uF 6.3V (20mm tall) Nichicon HNs, which have blown their tops.

(7 x 680) + (3 x 820) = 7220uF total
10 x 680 (if they only used the 680uF PSAs) = 6800uF total

A big fat 6% difference. Why did they do this???

Those aren't the only HNs, by the way. I found two of the same HNs (blown, again) near the RAM slots.

I take it that they are for the RAM, after seeing two MOSFETs and a ferrite coil near one.

I remember seeing a similar board where the two caps near the RAM were 560uF 6.3V (23mm tall ) Rubycon MCZs. So I should be able to use 560uF 4V polys there?

I don't see any other defective Nichicons on the board. Though there are 85°C general purpose caps, which have been known to fail in the past. None of those are bulging though.

Intel

[Shocker]

Re: I don't know what Intel was up to

I tricked it into staying on by jumpering the PSU.

VRM: 1.25V
HN at top of RAM slots: 1.29V
HN at bottom of RAM slots: 2.58V

I don't know whether these are the correct readings though.

The VRM makes a horrible whine and gets scorching hot .

I don't have a working soldering iron right now so even though I have spare caps, I'm unable to do a swap.

[mariushm]

Re: I don't know what Intel was up to

( nevermind )

[ben7]

Re: I don't know what Intel was up to

Don't run that thing like that, something bad with the VRM is likely to happen!!!

[Shocker]

Re: I don't know what Intel was up to

I'm not actually attempting to use the motherboard like this, I just did it to get numbers.

PSAs: 7mΩ / 7 caps = 1mΩ combined
HNs: 12mΩ / 3 caps = 4mΩ combined

Total: 0.8mΩ

I think something's wrong with more than the HNs, for the whine to get as bad as it is. Takes real talent to kill polys but I'm sure it's possible, so I'll replace both the HNs AND the PSAs to be safe.

I don't love Intel boards - I have a bunch of the D945GTP, and they have toasty VRMs (in the sense of getting extremely hot and discolouring the PCB ). Caps on those are 3 x 1200uF KZEs on 12V and 9 x 560uF 2.5V PSCs (with a position for a 10th) on Vcore. My PC has one, but that's because they were the best I had at the time.

EDIT: I found a thread on the D865GBF with completely different readings for the caps near the RAM (2.1V and 5V).

[Wester547]

Re: I don't know what Intel was up to

What could make VRMs get so hot on a motherboard, besides a horrific power supply, no cooling, defective chips and/or capacitors on the motherboard itself, a slim case, hot hardware on the motherboard, or something like? D:

[ben7]

Re: I don't know what Intel was up to

What could make VRMs get so hot on a motherboard, besides a horrific power supply, no cooling, defective chips and/or capacitors on the motherboard itself, a slim case, hot hardware on the motherboard, or something like? D:

Hm, bad design? xD

They might have sacrificed efficiency for cost, or just designed it to barely cope with the load requirements.

[momaka]

Re: I don't know what Intel was up to

What's the date code on those tall HNs?
I wonder because I recapped a Dell GX270 board last winter with the same tall HNs (got them used from an Xbox 360). Haven't had any problems, but I'd rather tear it down now and fix it properly rather than wait for something to fail.

[Shocker]

Re: I don't know what Intel was up to

What could make VRMs get so hot on a motherboard, besides a horrific power supply, no cooling, defective chips and/or capacitors on the motherboard itself, a slim case, hot hardware on the motherboard, or something like? D:

If you mean the D945GTPs, then to be fair, they did use Macron power supplies (specifically MPT-401s, but there's little difference between any of them) which I find to be as prone to cap failures as the old Fuhjyyu-ridden Antecs were. The Macrons don't get as hot as the Antecs, but they almost always use general purpose capacitors (like Fuhjyyu TN series) which are overstressed, making them fail even faster. And the case cooling wasn't too great either - two very slow 80mm Power Logic sleeve bearing fans (but I haven't seen a dead one yet), but at least it wasn't totally nonexistent. The fact that the KZEs are in the discoloured area doesn't help.

The VRM there has 4 phases - and the low-side MOSFETs are standing up from the board .

As for the D865GLC, there wasn't discolouration in the VRM, but it's only a matter of time. The PSU I used for the tests was an MPT-400 that I recapped earlier using Rubycon ZLH (6 x 2200uF 6.3V 10mm), Panasonic FR (1 x 3300uF 16V 12.5mm and 2 x 220uF 16V 6.3mm), Chemi-con KZE (1 x 470uF 25V 8mm), and Panasonic ED primaries (2 x 680uF 200V 22mm).

[c_hegge]

Re: I don't know what Intel was up to

I saw this once with a D954GNT (the VRM getting red hot and a discoloured PCB). I don't know what its history was, though. It could have been used with a junk PSU, or maybe it did have bad cooling. I got the board used from fleabay. It only lasted about a month after I got it before the VRM shorted totally.

My brother has a D945GTP in his PC. I got it used, and it doesn't have any evidence of heat discolouration anywhere on the board, and the VRM runs much cooler.

My theory is that since they only have two VRM in caps (as opposed to the 3 or 4 which many other boards have), they are more easily damaged by a bad PSU.

[momaka]

Re: I don't know what Intel was up to

^ I don't think dirty power from bad caps in a PSU can cause that alone. Mostly likely just crappy design on Intel's part. Standing MOSFETs without any kind of heat sink is asking for trouble. The GX270 boards have those, but there's a heat sink mounted on the board so it's not a problem.