How to Buy a PC Without Being Fooled
By Gabriel Torres on February 2, 2006


Introduction

If you are thinking on buying a new PC it is good to follow our tips in order to be not deceived. In this tutorial we will talk about the most common problems you can face when buying a new PC and also we will teach you how to check, without opening the computer case, if the PC you bought is really the one you ordered.

Our main tip is to check all hardware specs from your PC as soon as you get it, so see if they match to the specs you ordered. Since almost always the warranty is void if you open your computer, you will need to run a hardware identification utility in order to list all parts your computer have (CPU, motherboard, video card, memory, hard drive, etc).

There are several programs for this purpose available, like Sandra, Hwinfo and Everest (all available on our downloads section). We will show you how to identify the parts from your computer using Sandra.

Donwload, install and run Sandra. Click on the System Summary icon. The screen shown in Figure 1 will be presented.

Checking Your PC
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Figure 1: Detecting your computer parts using Sandra.

At Processor you can check which CPU is installed on your computer (at Model) and what is its clock rate (at Speed). Remembering that on AMD processors the CPU number isn’t its clock rate. As you can see in Figure 1, our CPU was an Athlon XP 2800+, which was running at 2.09 GHz.

You can check the CPU L2 cache size at L2 On-Board Cache. This information is important when you are checking AMD CPUs (for example, there are Athlon XP 2800+ models with 256 KB and 512 KB, each one running at a different clock rate).

Regarding AMD processors, we have already written several tutorials with reference tables listing the CPU real clock. If your system is based on an AMD CPU, check on the tutorials listed below what is the real clock your CPU should be running and check if your CPU is running at its correct clock rate or not:

Small differences between the clock your CPU had to be running and its actual clock rate can exist. This is perfectly normal. For example, a CPU with a labeled 3.06 GHz clock rate running at 3.05 GHz is normal. The difference can also be on the other way. Athlon XP 2800+ runs at 2.08 GHz but on our machine it was running at 2.09 GHz (see Figure 1). The problem is when you find an absurd difference, for example a 3.2 GHz CPU running at 3 GHz.

At Mainboard you can see what is the manufacturer and model of your motherboard. In our example in Figure 1 our motherboard was a Gigabyte GA-7VAXP Ultra.

At Mainboard, Total Memory you can check the total amount of RAM memory installed on your PC. On our example our system had 512 MB RAM.

At Video System, Adapter you can check what video card is installed on your system. On our example our video card was a GeForce FX 5700 Ultra.

At Physical Storage Devices you can check the disk drives installed on your system. In our case we had one 114 GB hard disk drive from Maxtor (model 6Y120L0, sold as 120 GB), one 75 GB hard disk drive from Western Digital (model WD800LB, sold as 80 GB), one USB flash drive (“pen drive”) and a DVD recorder from LG model GSA-4160B.

It is very important to notice that hard disk manufacturers label their products with a capacity above their real storage capacity. As you can see on our example, our 120 GB hard drive was in fact a 114 GB hard drive and our 80 GB was in fact a 75 GB hard drive. This happens because hard disk drive manufacturers define 1 GB as being 1 billion bytes and 1 MB as being 1 million bytes, while in fact 1 GB is 2^30 bytes (1,073,741,824 bytes) and 1 MB is 2^20 bytes (1,048,576 bytes). The difference between what the manufacturers define as being GB and MB and their real numbers makes the labeled hard disk drive capacity to be “inflated”. So, losing some gigabytes on your hard disk drive when checking your hardware parts is perfectly normal.

You can navigate on the other options available on the program to collect even more details about your new PC.

Let’s now talk in details about the most common problems faced by users when buying a new PC.

Video Card

The video card is the easiest PC part to be deceived, especially if you decided to buy an entry-level board, like GeForce FX 5200, GeForce FX 5500, GeForce 6200 or GeForce 6600.

Almost all mid-range and high-end video cards follow the same specs. This means if you buy a GeForce 6600 GT from manufacturer A it will have the same specs and performance as a GeForce 6600 GT from manufacturer B.

The problem with low-end video cards is that NVIDIA doesn’t set standard clock rates or a memory bus width (number of bits to be used to access video memory). This problem is particularly common with the chips listed above.

For those cards, you can find models accessing memory at 32-, 64- or 128-bit rate. Different clock rates can be used. On the market you can find GeForce 6600 models accessing memory at 400-, 500-, 550- and 600 MHz, for example.

What happens: you buy a GeForce 6600 without paying attention to these details to learn later that your GeForce 6600 is slower than the GeForce 6600 of your friend, cousin or neighbor, since it uses a different clock or memory configuration – and maybe you decided to buy a GeForce 6600 exactly because you wanted a computer identical to your cousin’s.

The solution? To specify at the store the brand and the exact model that you want to buy. “GeForce” is the name of the chip, and NVIDIA manufactures only chips, not boards. Video boards are manufactured by other companies like XFX, Prolink/Pixelview, Gigabyte, Leadtek, eVGA, MSI, ASUS, etc. At the manufacturer’s website you can obtain the number of the exact model you want to buy and ask for that specific model, checking later if your PC came with this model.

Low-end video cards from ATI are easier to be identified, since 64-bit models are labeled as “SE” (e.g., Radeon 9200 SE) and ATI doesn’t allow video card manufacturers to change the clock of the video card based on their products.

To check the clock rate of your video card you should run PowerStrip program, which can be downloaded at our downloads section. Video cards have two clocks: the clock used internally by the video processor (GPU) and the clock used by the video processor to access the video memory. You need to check both. In Figure 2, you can see that our GeForce FX 5700 Ultra was running at 500 MHz with its memory running at 1 GHz.

VGA clock
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Figure 2: Checking the clock rates of your video card.

How can you know the correct clock rates for your video card? Check this information on our tutorials NVIDIA Chips Comparison Table and ATI Chips Comparison Table. These tutorials have a complete list of all chips and their clock rates.

Notice that sometimes the clock rate reported by PowerStrip program is half the clock published on our tables. What happens is that nowadays video cards use memories with DDR technology, where two data chunks are transferred per clock cycle, doubling the performance compared to a system running at the same clock rate but transferring only one data chunk per clock cycle. Because of that usually manufacturers announce their memory clocks “doubled”. For example, GeForce FX 5700 Ultra accesses its video memory at 500 MHz but since it achieves a performance as if it were accessing it at 1 GHz (since it uses DDR technique) the manufacturer says that its memory clock is of 1 GHz, while this is not true. On our tables we published the “doubled” clock rates.

So, if PowerStrip lists a memory clock as being exactly half the memory clock rate shown on our tables, the clock rate is correct (this PowerStrip behaviour is particularly common when checking video cards based on ATI chips). Notice that this is only true for the memory clock, not being valid for the video processor clock (“core clock”).

We’d also like to remember that if you want to run games on your PC you should not buy a PC with on-board video (i.e., where the video is produced by the motherboard, also known as integrated graphics).

Power Supply

Another component that deserves your full attention in order to be not deceived is the PC power supply (PSU). For entry-level PCs, with on-board video or using low-end video cards like GeForce 6200 or Radeon X300 the power supply isn’t a critical component. But if you have a video card that requires an extra power supply connection (from GeForce 6600 GT up, from GeForce FX 5700 Ultra up, from Radeon 9700 up and from Radeon X700 XT up) choosing a good power supply is essential.

The main problem is that the majority of power supplies available on the market are wrongly labeled. We are tired of facing 180 W power supplies being sold as 400 W ones. And this isn’t an error made by the store: on the power supply label it is really written “400 W”. So, you can buy one power supply like this one believing that you are really buying a 400 W power supply and start facing “freezing” and reseting problems on your PC because the power supply isn’t being able to provide enough current to your PC.

To know the real power capacity of a power supply you need to add up the individual power capacity of each power supply output. On a given power supply you can find the following power capacities written on its label: 100 W (for +5 V and +3.3 V outputs), 96 W (+12 V), 2,5 W (-5 V), 6 W (-12 V) and 10 W (+5VSB). Adding up these values we could find that the real power capacity of this power supply is of 214.5 W. Amazingly enough this power supply was sold as “400 W”.

If you are buying a high-end system, our suggestion is that you don’t save money on the power supply and choose a “branded” one (also known as “real power PSUs”), like TTGI, Thermaltake, Cooler Master, Enermax, OCZ, Seventeam, just to name a few.

Learn more about this subject by reading our Power Supply Tutorial.

RAM Memory

RAM memory is a very important aspect to take care of when buying a new PC, since nowadays almost all PCs can use a technique called “dual channel”, which doubles the RAM memory performance.

In order to make this technique work, the motherboard has to support it and you also have to install RAM memory using two separated modules. For example, if you are buying a PC with 512 MB RAM, the ideal scenario is to buy two 256 MB modules. These two modules must be installed in separated memory channels. This is normally accomplished by jumping one memory socket: if you install the first memory module on the first memory socket on the motherboard, the second module must be installed on the third socket (and not on the second one).

So, when buying a new PC you have to check if your RAM memory was installed like this.

Nowadays all new computers based on Pentium 4, Celeron D, Pentium D, Athlon 64 (socket 939), Athlon 64 FX and Athlon 64 X2 support this technology.

Computers based on socket 754 (socket 754 Sempron and socket 754 Athlon 64 CPUs) don’t support dual channel mode. Socket 462 computers (socket 462 Sempron and Athlon XP CPUs) can support it or not, it will depend on the motherboard (you will need to use a motherboard based on nForce 2 Ultra or VIA KT880 chipsets in order to use this feature).

There are two ways to know if your PC is using or not DDR dual channel without opening it. One is paying attention to POST, which is what text-based screen that shows up just after turning your PC on. Usually when the RAM memory is installed on dual channel configuration something telling this condition will show up, like “Dual Channel Enabled” or something similar (see Figure 3). The PC portrayed in Figure 3 is with DDR dual channel scheme correctly enabled.

DDR Dual Channel
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Figure 3: Checking the number of memory channels used on POST.

The second way of checking whether DDR dual channel is enabled or not is through software. Everest is a very good choice for this. On it, go to Motherboard, Motherboard and check what is below “Memory bus properties”. “Bus width” item can be listed as “64-bit”, meaning that your PC is configured to use just one memory channel, or “128-bit”, meaning that your PC is correctly configured to use two memory channels. In Figure 4, you can see a PC using just one memory channel and, in Figure 5, a PC using two memory channels (DDR dual channel).

Single Channel
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Figure 4: This PC is using just one memory channel.

DDR Dual Channel
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Figure 5: This PC is correctly using two memory channels.

For more information on this subject, read our tutorial Everything You Need to Know about DDR Dual Channel.

Originally at http://www.hardwaresecrets.com/article/How-to-Buy-a-PC-Without-Being-Fooled/279


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