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Author : kyoshiro mibu
Article ID : 55
Audience : Top News
Version 2.00
Published Date: 2005/2/20 22:41:29
Reads : 5631

Click to see original Image in a new windowPCI-Express vs Conventional PCI and PGA vs LGA

Quite a few of us gamers are getting antsy with the new motherboards out there. Personally I prefer Gigabyte Motherboards to almost anything else. Abit would be my second choice followed by Asus. But what makes these boards so fantastic or pathetic? Well, the presence of PCI-Express and LGA! This is critical knowledge to have before investing in a new board or card!

Make sure to check out these sites: www.Express-Lane.org , www.Intel.com
and www.PCI-SIG.org for info on these new standards!

Click to see original Image in a new windowFor those of us hard up on gaming and a lot of processing power PCI-Express and LGA open avenues only recently developed. So what’s the distinction between PCI-Express and PCI?

Well, PCI was introduced in 1992 to be the 32-bit answer to the old ISA/EISA and VESA Local Bus. After PCI came out there were a few cards developed for graphics but they were nothing special. Also, PCI was only clocked at 33MHz. So what was the result? The GPU’s (Graphics Processing Unit) could be as fast as the designers wanted. But it can only process data as fast as the bus can spit it out. SO, they needed a way to hype up the clock speed.

The AGP (Accelerated Graphics Port) was the answer. At first only multiples of 2x and 4x were available. But then 8x came out. This gave us the ability to push 33MHz time 8 into a GPU! That’s 264MHz, quite a substantial improvement over PCI cards.

However, this is not enough. I recently purchased the Gigabyte 915G PRO motherboard. It has a AGP slot and a PCI-Express graphics slot. The difference?

Click to see original Image in a new windowAGP = 264 MHz (so I bought a $350.00 ATI 9800XT PRO 256 MBDDR-RAM)
PCI-Express = 2.5 GHz (I bought a $150.00 NVidia 6600GT Sparkle with 128MB DDR3 RAM)

Which benchmarks better? The NVidia! Maybe the fact the PCI-Express has 10 times the speed and that DDR3 ram is far more powerful than the stuff ATI uses. And it cost less than half!

I’m sure you’re wondering how PCI-Express is so much better than PCI or AGP. It’s pretty simple. A Serial Bus. See, with PCI they used the Parallel bus model. This means they were transmitting up to 32 one’s and zero’s at the same time. Well, the only way to make PCI faster was to increase the number of one’s and zero’s being pumped out (which resulted in 64-bit PCI in servers) or to increase the clock speed (which led to the 66-MHz PCI bus). However, when doing all this you drastically skew the time frame in which the signals arrive at their destination. In other words, the bulkier and faster your signal got, the sloppier it became which resulted in a very high error rate.

PCI-Express, however, has only 4 wires! One pair for transmit and one pair for receive. Additionally, PCI-Express uses encapsulation of the data being sent. So PCI-Express very nearly uses packets to deliver information. This is sweet because each packet contains a CRC segment which ensures error-free transmission!

The end result? Up to 80 Gbps data throughput. Not to mention, no more Southbridge. With SATA/SAS Harddrives becoming more and more common and gigabit Ethernet coming out in homes, the slow stuff is dwindling.

To explain PCI-X 266/533; these were PCI-Express upstarts the hit 266MHz and 533MHz. They were around shortly but were phased out by PCI-Express.

Click to see original Image in a new windowA suggestion to anyone buying a card or motherboard: go to www.Express-Lane.org and download the 4 videos they have there about PCI-Express. The vids are by Intel and are designed to explain this new technology. These are a must see!


With your older CPUs PGA was the standard (PGA = Pin Grid Array). Remember, the little white square on your motherboard that is filled with holes? Great design! You bend one pin on the CPU and you can count on buying a new one, right?

Well, when I bought my CPU I made sure it was a P4 3.4GHz. I had a nice Abit board (478P chipset). I opened up the CPU box, raised the arm on my Abit’s ZIF socket and set the CPU down. I lowered the arm, picked the board up and the CPU SLID OFF! Upon picking my jaw up off the floor, I examined the CPU to find it had NO PINS on it. At first I was pissed and thought I had a defective CPU. But I noticed an orange logo that said “LGA775” on the CPU box. After doing some research I made a discovery: I had accidentally bought a new LGA CPU. But I had a new Abit PGA board.The solution? :Sigh: Well, I sold my brand new Abit board to a friend and bought my Gigabyte board.
Finally, afterabout $700.00 having been blown I was set.

When I got the Gigabyte board, sure enough the socket for my LGA chip and VASTLY different than anything I had ever seen before. There were hundreds upon hundred of tiny little pins in the socket, sticking up. Also there was a rather hard-core trap door I had to raise to get the CPU in. So I inserted the CPU, lowered the door and pushed the arm down and it made a loud *CRUNCH*. I about had a heart attack. I did NOT just ruin my new toys! Well, it’s supposed to make that sound. A key thing here, you can only insert and remove an LGA chip 20 times or you’ll ruin the LGA socket.

That in mind, what’s the benefit of LGA? It’s much faster because the pins are much smaller than in a PGA. The smaller the pins, the less distance electrons have to travel and the faster they go!

So, get out your wallets and start upgrading!


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