I am looking at upgrading my currect PC with a faster CPU. I am 90% sure that the CPU I ordered will work in my current mobo, but I thought I'd ask here just to be 100% sure. I can return it if it does not work, but the time frame for returns is very small. My mobo is an Intel D850EMV2 and I currently have a P4 2.4B GHZ 533MHZ FSB based on the .13 micron process with a 512K L2 cache socket 478. I ordered a P4 2.8A GHZ 533MHZ FSB based on the 90nm process with a 1MB L2 cache socket 478 (Prescott). According to the supported processor page for my mobo on intel.com it supports P4 chips up to 2.8GHZ with 533MHZ FSB (for the revision of the board I have) with 512K L2 cache. Problem is intel stopped supporting that board in 2003 and this revision of the chip was released in 2005 so it wouldn't be on that list even if it is compatible. Everything matches except the L2 cache size and the die process used to make the chip. This is the only socket 478 533MHZ FSB P4 chip I could find, so it's either this chip or stick with my old one. Will it work?

Buying another (S478) P4 was not the smartest move. You should have stayed with what you had and hold off till you can afford a motherboard/CPU upgrade. If I were you I'd pull the plug on the whole deal while you still can.

I agree with Sabertooth. What did the CPU cost...$150-175? It's definitely not a cost effective upgrade, especially on a system running RAMBUS. You may find that the Prescott isn't even supported & then you'll be stuck with it, or you'll have to pay return shipping + restocking fee. You should have asked BEFORE you ordered it.

I did jump the gun on ordering the chip, I tend to do that sometimes, it's a personal fault... I did, however, know that this wasn't a really cost effective upgrade, but chose to do it anyway. In the end, I'll be out ~20 bucks if it doesn't work, so it's not really a big deal.

I think the reason why it doesn't work is because the 2.8A is a prescott and you have the northwood motherboard... Problem with prescott is they draw more current than northwood does and if your motherboard cannot supply enough amerage to satisfy the prescott requirement, then the prescott may not work in your motherboard... I think you are better to buy a Northwood 2.8Ghz instead of a Prescott, but like the post above, upgrading from 2.4 to 2.8Ghz and spending $150-$175 isn't worth the trouble. However, you had 1GB of PC800 RDRAM, and if you want to buy a new motherboard with new CPU, new RAM is also required and perhaps new power supply and new video card (PCI-E for future proof)... If you can exchange the 2.8A for a 2.8Ghz Northwood (533Mhz FSB version) without any charge, then do so... TMP-Man Asus P5P800-SE P4 506 2.66Ghz @ 4100Mhz 1.525v Thermaltake CLP0024 w/ 2000RPM FAN 1024MB DC Corsair DDR400 40GB 5400RPM/120GB 7200RPM HD 128MB Radoen 9500 mod 9700 @ 360/585