Thankyou Rit.

And Captain, I haven't seen those in a while either, but as I said after spending almost a week trying to figure out what is wrong; I am just sending it back for warranty. But thankyou nonetheless for your valuable input.

I'll let you guys know what happens next with regard to progress on this issue, Best Regards to everyone.

Using the vernacular of the day....WTF!
60-90C for a P35 northbridge is insane. The lower-mid end of that scale is usually reserved for nVidia's SPP's (northbridge/chipset). The hottest boards I have ever owned were both 680i SLI mobo's (EVGA and Asus) and both topped out at around 75C (and that's with overclocked/overvolted RAM) -active overboard cooling is a must at that temp. A P35 chipset working hard with overvolted RAM sitting above a hot GPU would likely max out at 50-55C, maybe 60C under a full load stress test. If the boards system sensor is not out of whack then something is amiss.
Technically the Intel guy is right- most Intel chips are rated 100-110C (P35 is 106C - beware link is a pdf)...but still

That link gives error when I try to open, but your words are sufficient for me. I really appreciate your time and help DBZ.

Well guys as it turned out the store from where I purchase my IT stuff has told me that Intel do not have any similar motherboard to replace my damaged one (only have DG43NB in stock, which is inferior in some specs, except chipset I guess). Hence, came the offer to pay the difference and get Asus P5Q Deluxe motherboard, and I've gone for it, it should be here today sometime,then the painful process of reinstalling everything ........ again.

DG? That's integrated graphics, yes?

yes, with PCI Express x16 slot (I am assuming as I haven't really bothered to check it as I just don't want to have any integrated VGA board right now).

Never Take Anything for Granted.....

By all means, stay away from it. It could only bring you heartache, frustration, and pain.

Did I ever tell you how Emachines punked me by leaving the entire PCI-E socket out of the Intel 915GAG board in my T-5026? Boy, did I feel dumb when I had to go to CompUSA to return the video card.

Ouch
Its painful just to read that man !

Alright guys, I have received the replacement motherboard and guess what ..... they've somehow found another DP35DP from somewhere so I ain't getting the Asus one I asked as second option.

Anyway, I have reinstalled almost everyonething generally I used, however, there seems to be two issues I am unable to understand at this moment:

i- The CPU temperature/margin (as stated by Intel's IDU Utility & also BIOS) stays at 26C even at under full load; how can this be possible? it was the same on the older board as well.

ii- The GPU idle temperature at ambient room temperature of roughly 24-25C range is 58C; and under full 100% load it goes upto 78C. The upper figure seems to be alright to me, but the idle temp just seems bit too high, any ideas please?

Thanks for sticking with me through this

Sounds like the CPU temp sensor is fritzed, especially since it's the identical temp on both boards - better than the E8400/8500 sensors that read 99C I suppose.

The idle temp I presume is for the HD 5770 ? Sounds very high. What fan speed at 58C ?

I've not tempered with default settings; and let it stay at 'Auto', however the AfterBurner software came with it, telling me the fan speed is 46% right now with core speed at 400MHz and Idle temperature hovering at 57-58C.

other temperatures are:

Motherboard = 38C
Memory Controller Hub = 66C (seems higher but were similar with the old board)
I/O Controller Hub = 84C (Again seems higher but were similar with the old board)

Processor Fan Speed = 3241 RPM

Except for the motherboard PCB all the temps seem high-although from memory I think most Intel boards only have small aluminium heatsinks on top of thermal tape/pads so maybe the chipset/ICH temps are ballpark for the board.
Anything that could contribute- Chassis cooling ok ? (fans working/filters clean), high ambient temps ?
BTW: Did you get a new replacement or a refurbished one?

New replacement motherboard.

You are right, Intel boards only have small aluminum heat-sinks and probably that is the reason for higher temps. Perhaps I can get some small fan which can be fitted on top of that heat-sink I guess.

There are three fans on the side panel (one 120 mm, two smaller fans) + one at the back, there is none in the front as unfortunately the casing doesn't provide option for that, but it does have few air intake openings to maintain airflow.

I have ran a small experiment since my last post, I opened up an 5.4" bay slot and moved one of the two dvd drives in that creating space for air to freely flow directly inline with the backside fan. What this did was immediately reduced the GPU's temp to 53C at idle. But as soon as I ran FF (3.6.3) the temperature shot back up to 56C (fan speed at 39%) while nothing else is running.

This slight re-arrangement has also dropped the I/O Controller Hub temperature to 78C at idle (re-enforcing my view that a small fan will probably reduce it further).

Sorry man, but this is how I feel about the whole sordid affair: http://www.newegg.com/Product/Product.aspx?Item=N82E16813128372

Gigabyte, for fast, fast, fast relief! And here you thought it was Rolaids.

Yup thats pretty good one captain, but as I got the new replacement board for free (except for the transportation charges) I guess it was worth it.

Frankly, I have been thinking about bringing my upgrade plans forward from some time 2H next year to bit earlier if this thing doesn't hold up again. The board worked perfectly right out of the box by the way. Except for the GPU Idle temperature, and CPU temperature sensor probably died as DBZ pointed out earlier, I don't have any more Issue at the moment.

Also, in 22 years only two motherboard's have died on me including this one, so I can't complain about it in general

Anyway, the graphics card creates a pocket of still air under it, so I/O CH temperature increases should be anticipated. (This is a comparison of same board with integrated vs after the installation of an add in video card).

Side fans tend to create a boundary layer by compressing air against the board. As you've explained it, there's no front fan, so lack of cross flow likely aggravates the situation. The pocket of air under the video card is dealt with in the Antec 900 case with vented PCI slot covers, but in most cases they're solid.

My personal experience was that with a side fan directly on the case side (Antec Mid-tower/ Intel G965) Southbridge temps increased. So, I placed it prior to the CPU ducting and the temps reduced. This was fun since the side fan then acted as a "turbocharger" to the stock Intel HSF. Noisy, but muy cool.

If this is already obvious, please accept my apologies.

This board will likely never be back in stock (DDR2); http://www.newegg.com/Product/Product.aspx?Item=N82E16813128359 But, check out the heat sinks on that sucker!

It seems that somebody hasn't been buying enough Emachines.

I was thinking on the similar lines as well Captain and have moved one of the fans as such. However, keeping in mind your experience I think I'll need to make few more openings to improve the airflow further.

The first thing I noticed on that board was heatsinks, and frankly 'said few colorful words' about Intel for not doing a good job in this area.

Yup luckily, I've always selected what components I want to buy, then went ahead and put them together, and since the days of 486DX-100 I never bought non-Intel boards for one reason only, they are simple (read over engineered as DBZ rightly said) no frills solution, also generally are very very stable and reliable platforms. Thanks you